Recipe Overview
Why you’ll love it: Indulge in the ultimate comfort food with this Cheesy Brussels Sprouts au Gratin. Each bite offers tender Brussels sprouts enveloped in a rich, bubbling Gruyère cheese sauce, creating an irresistible side dish that’s perfect for any special occasion. While it shines brightly on a Thanksgiving table, its deliciousness makes it worthy of enjoying any time of year.
How long it takes: 15 minutes to prepare, 40 minutes to bake, plus 10 minutes resting time.
Equipment you’ll need: A 9×13 inch baking dish and a medium saucepan are essential for creating this delightful gratin.
Servings: This recipe yields 8 generous servings, making it ideal for family gatherings or holiday feasts.
Irresistible Cheesy Brussels Sprouts au Gratin: The Ultimate Holiday Side Dish
As the days grow shorter and the crisp autumn air signals the arrival of fall, our thoughts inevitably turn to comforting, hearty meals. It feels like just yesterday we were enjoying summer barbecues and refreshing salads, but a quick trip to the grocery store confirms it: the season of root vegetables, gourds, and savory greens is here. From vibrant winter squash and crisp apples to earthy pumpkins and robust cabbage, fall brings a bounty of flavors that warm the soul. And among these autumnal treasures, Brussels sprouts stand out, especially when transformed into this unbelievably delicious Cheesy Brussels Sprouts au Gratin.
This isn’t just any Brussels sprouts recipe; it’s a culinary masterpiece that will convert even the most skeptical eaters. Imagine tender Brussels sprouts, lightly roasted to bring out their natural sweetness, then generously coated in a luxurious, creamy Gruyère cheese sauce. Infused with subtle hints of aromatic nutmeg and fragrant thyme, this magnificent concoction is then baked to golden perfection until it’s bubbling and lightly browned on top. The result is a side dish that is truly a delight for the senses – rich, savory, and utterly irresistible. While it’s destined to be a star on your Thanksgiving table, don’t wait for a special occasion to experience the magic of this gratin. It’s perfect for any dinner where you want to add a touch of gourmet comfort.
What Makes This Brussels Sprouts Gratin So Special?
At its heart, this dish is a classic “gratin.” But what exactly does that mean? Originating from French cuisine, the term “au gratin” literally translates to “by grating,” historically referring to a dish topped with grated breadcrumbs or cheese and then baked until a golden-brown crust forms. Over time, it has evolved to encompass any dish prepared in a shallow baking dish, typically featuring vegetables, potatoes, or even seafood, covered with a savory topping and baked until bubbly and browned. Essentially, a gratin is a type of casserole renowned for its enticing crust and rich, comforting interior.
And let us assure you, this Brussels sprouts gratin embodies everything wonderful about the “au gratin” tradition. We’ve often found ourselves scraping the baking dish for every last, savory morsel. During recipe testing, the aroma alone was enough to make us impatient, and the first taste confirmed it: pure culinary bliss. Even those who claim to dislike Brussels sprouts are often converted by the creamy texture, the rich Gruyère flavor, and the perfectly cooked sprouts in this mouthwatering gratin. It’s a game-changer that transforms a humble vegetable into an elegant and universally loved side.
Brussels or Brussel? Settling the Spelling Debate
There’s a common point of confusion when it comes to spelling the name of this delightful, tiny cabbage-like vegetable. Many people mistakenly omit the final “s,” referring to them as Brussel sprouts. However, these distinctive vegetables are actually named after the capital city of Belgium, Brussels, which proudly features an “s” at the end. Therefore, the correct spelling is always Brussels sprouts. We certainly wouldn’t want to inadvertently offend the wonderful people of Brussels by misnaming their namesake veggie!
Key Ingredients for a Perfect Cheesy Brussels Sprouts Gratin
Crafting the perfect gratin begins with selecting high-quality ingredients. Each component plays a vital role in achieving the rich, creamy, and flavorful result that makes this dish so irresistible.
- Brussels Sprouts: The star of our dish! Aim for fresh, firm, and vibrant dark green sprouts. Avoid any that appear shriveled, have yellowing outer leaves, or show signs of wormholes. You’ll need about two pounds, which typically equates to two standard bags from the produce section. Freshness is key for the best texture and flavor.
- Olive Oil, Salt, and Pepper: These basic seasonings are crucial for bringing out the natural flavors of the Brussels sprouts during their initial roasting. A light toss with olive oil ensures even browning and helps the salt and pepper adhere beautifully.
- Onion: A medium yellow cooking onion provides a foundational aromatic sweetness to the cheese sauce. While yellow onions are recommended, white or even Vidalia onions can also work, offering slightly different notes of sweetness. Ensure it’s finely diced to melt seamlessly into the sauce.
- Unsalted Butter, All-Purpose Flour, and Whole Milk: This trio forms the classic béchamel sauce, which is the luscious base of our gratin. Unsalted butter allows you to control the seasoning, while all-purpose flour thickens the sauce to the perfect consistency. Whole milk contributes to the sauce’s rich, creamy texture and decadent flavor. For a slightly lighter version, you could use 2% milk, though it will yield a less indulgent sauce.
- Thyme: This herb adds a wonderful earthy and slightly floral note that pairs exceptionally well with both Brussels sprouts and Gruyère cheese. Fresh thyme is always preferable for its vibrant aroma, but if dried is all you have, remember that it’s more potent; use half the amount specified for fresh.
- Nutmeg: A pinch of freshly grated nutmeg is the secret ingredient that elevates the cheese sauce, adding a warm, subtle spice and a gourmet touch. The difference between pre-ground and freshly grated nutmeg is truly remarkable; seek out whole nutmeg and use a fine grater for the best flavor experience.
- Gruyère Cheese: This magnificent hard Swiss cheese is the cornerstone of our gratin’s incredible flavor. Unlike traditional Swiss cheese, Gruyère is denser, lacks large holes, and boasts a wonderfully nutty, slightly earthy, and sharp flavor. It melts beautifully, creating a smooth, velvety sauce and a golden, bubbly crust. Its robust flavor stands up perfectly to the Brussels sprouts, making it an ideal choice for this dish.
Mastering Brussels Sprouts Preparation
Properly prepping Brussels sprouts is essential for ensuring they cook evenly and absorb all the delicious flavors of the gratin. While it might seem a bit daunting the first time, it’s a straightforward process that will quickly become second nature.
- Selection is Key: Begin by choosing the best sprouts. Look for those that are firm to the touch, compact, and a vibrant dark green. Avoid any that feel soft, appear shriveled, or have outer leaves that are yellowing or damaged.
- Thorough Rinse: Place your chosen Brussels sprouts in a colander and rinse them thoroughly under cool running water. This removes any dirt or debris that might be clinging to the outer leaves.
- Trim the Stem: Using a sharp paring knife, carefully trim off the tough, woody stem end. You want to cut just enough so that the stem is flush with the bottom of the sprout, allowing it to cook more evenly without falling apart.
- Peel Outer Leaves: Gently peel away any discolored, bruised, or wilted outer leaves. These can be bitter or tough, and removing them ensures a more pleasant eating experience.
- Halving for Flavor: For this particular gratin recipe, it’s crucial to cut the sprouts in half lengthwise. This isn’t just about making them bite-sized; halving them exposes more surface area, allowing the creamy Gruyère sauce to thoroughly permeate each tender morsel, ensuring maximum flavor in every bite. If you have particularly large sprouts, you might even consider quartering them for uniform pieces. The goal is consistent, manageable pieces.
- Visual Aid: If you’re a visual learner and prefer to see the process, consider watching this informative YouTube video for a clear demonstration of how to prep Brussels sprouts.
Crafting Your Cheesy Brussels Sprouts Gratin: A Step-by-Step Guide
Making this Cheesy Brussels Sprouts au Gratin is a rewarding process, combining simple techniques to create a dish of profound flavor and comforting warmth. Follow these steps for perfect results every time:
1. Prep All Ingredients (Mise en Place): Before you even turn on the stove, ensure all your ingredients are prepped and measured. This “mise en place” approach makes the cooking process smooth and stress-free. Have your Brussels sprouts trimmed and halved, Gruyère cheese shredded, milk measured, butter and flour ready for the roux, nutmeg freshly grated, and thyme chopped. This organized approach prevents rushing and ensures each step flows seamlessly.
2. Preheat Oven and Prepare Baking Dish: Set your oven to 400ºF (200ºC). Select a visually appealing 9×13-inch baking dish, ideally one made of glass or ceramic, as this gratin will be served directly from it. Lightly spray the dish with nonstick baking spray to prevent sticking and aid in cleanup.
3. Roast the Brussels Sprouts: In a large bowl, toss the prepared Brussels sprouts with a tablespoon of olive oil, a quarter teaspoon of kosher salt, and an eighth teaspoon of ground black pepper. Spread them in an even layer in your prepared baking dish. Roast them in the preheated oven for approximately 20 minutes, or until they are just beginning to soften and show a slight browning on the edges. This initial roasting step develops their flavor and gives them a tender-crisp texture before they are smothered in sauce.
4. Prepare the Creamy Gruyère Sauce: While the Brussels sprouts are roasting, turn your attention to the stovetop and begin making the luxurious cheese sauce. In a medium saucepan over medium heat, melt the unsalted butter. Add the diced yellow onion and sauté, stirring constantly, for about 2 minutes until the onion becomes translucent and fragrant. Next, whisk in the all-purpose flour, creating a roux, and continue to stir or whisk for another minute to cook out the raw flour taste. Gradually, pour in the whole milk, whisking continuously to prevent lumps. Continue to cook over medium-low heat, stirring frequently, for 10 to 12 minutes, until the sauce has visibly thickened to a rich consistency. Remove the saucepan from the heat, then stir in the fresh thyme and freshly grated nutmeg, ensuring they are well combined. Finally, add half of the shredded Gruyère cheese, stirring gently until it has completely melted into the sauce, creating a silky-smooth, intensely flavorful cheese mixture.
5. Assemble and Final Bake: Retrieve your partially roasted Brussels sprouts from the oven. Carefully pour the creamy Gruyère cheese sauce evenly over the sprouts, stirring lightly to ensure every sprout is generously coated. You might be tempted to taste a spoonful (and we wouldn’t blame you – it’s incredibly good!), but resist the urge to eat it all! Sprinkle the remaining shredded Gruyère cheese over the top, which will form a beautiful golden crust. Return the dish to the oven for another 20 minutes, or until the top is lightly browned, the sauce is bubbling vigorously around the edges, and the cheese is melted and golden.
6. Cool Before Serving: Once baked, remove the gratin from the oven. Allow the casserole to cool and set for 5 to 10 minutes before serving. This brief resting period allows the sauce to thicken slightly and prevents it from being too runny when scooped. Serve this magnificent Cheesy Brussels Sprouts au Gratin directly from the baking dish, letting its rustic charm and enticing aroma captivate your guests.
Elevate Your Gratin: Delicious Recipe Variations and Expert Tips
While this Cheesy Brussels Sprouts au Gratin is perfect as is, it’s also wonderfully adaptable! Don’t hesitate to experiment with these variations to suit your taste or what you have on hand.
- Try a Different Cheese: The slightly nutty and robust flavor of Gruyère is undoubtedly superb in this gratin, but other cheeses can create equally delicious results. Consider substituting with a sharp Swiss cheese for a similar profile, or try sharp cheddar for a more classic, tangy flavor. Parmesan or Asiago would also add a delightful salty, umami kick, particularly when mixed into the sauce or sprinkled on top.
- Add Savory Bacon or Pancetta: For an extra layer of smoky, salty richness, incorporate crispy bacon or pancetta. Simply cut your chosen meat into roughly 1-inch pieces, cook until beautifully crisp, then drain off any excess fat. Stir the cooked bacon or pancetta into the cheese sauce along with the thyme and nutmeg for an incredibly flavorful addition that will enhance the dish’s depth.
- Experiment with Spices and Herbs: Don’t be shy about customizing the seasonings! If you adore garlic, a teaspoon of garlic powder added to the white sauce will infuse it with a pungent warmth. A pinch of smoked paprika could be a fantastic addition, perhaps even sprinkled on top before baking to add a lovely color and a hint of smoky sweetness. If nutmeg isn’t your favorite spice, feel free to omit it; the gratin will still taste fantastic with the other flavors shining through.
- Lighten it Up: For those looking to reduce calories and fat, you can still enjoy a delicious gratin. Substitute whole milk with low-fat milk (such as 1% or 2%) when making the white sauce. While it might be slightly less creamy, it will still offer a satisfying richness. If you’re serious about cutting calories, try reducing the amount of cheese mixed into the white sauce, perhaps adding just a half-cup sprinkled over the top before baking for that essential golden crust.
- Not a Fan of Brussels Sprouts? Try an Alternative Gratin: If Brussels sprouts simply aren’t your thing, the concept of a cheesy gratin is versatile. Consider making scalloped sweet potatoes with bacon and Gruyère for a sweet and savory delight, or a creamy asparagus casserole for another fantastic vegetable-based side dish.
Explore More Brussels Sprouts Delights
If your only experience with Brussels sprouts involves sadly boiled, overcooked versions, you’re missing out on a world of flavor! Modern recipes have revolutionized how we enjoy these nutritious little cabbages. If you’re seeking everyday options that highlight their delicious potential, venture into trying crispy grilled Brussels sprouts, quick and easy air fryer Brussels sprouts, or perfectly tender sautéed Brussels sprouts with pancetta.
Brussels sprouts also shine beautifully in salads, offering a refreshing twist similar to coleslaw. You’ll love this vibrant shaved Brussels sprouts salad with grapes and Parmesan, or the festive Brussels sprouts salad with apples, cranberries, and walnuts for a seasonal crunch. Roasted Brussels sprouts have become a staple on restaurant menus, and for good reason—their caramelized edges and tender centers are truly addictive. For a delightful sweet and spicy kick, try our roasted Brussels sprouts with maple & cayenne!
Make-Ahead Ideas
Preparing components of your Cheesy Brussels Sprouts au Gratin in advance can significantly reduce stress on a busy day, especially when hosting. You can get a head start by prepping the Brussels sprouts up to two days before you plan to bake. After trimming and halving, store them in an airtight container or a resealable bag in the refrigerator. Similarly, dice the onion ahead of time and store it separately in a covered bowl. Shredded Gruyère cheese can also be prepared up to a week in advance and kept refrigerated, ready for assembly.
Storage & Reheating Tips
While this gratin is truly at its best when enjoyed fresh from the oven, any leftovers can still be savored. Store any remaining gratin in an airtight container in the refrigerator for up to 2-3 days. To reheat, you have a couple of options: gently warm it in the oven at 300°F (150°C) until heated through, which helps maintain some of its crispy top, or for a quicker reheat, use the microwave. Be mindful not to overheat in the microwave, as this can make the sauce oily. Cover loosely and heat in short bursts, stirring occasionally, until warm.
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Cheesy Brussels Sprouts au Gratin
Rachel Gurk
15 minutes
40 minutes
10 minutes
1 hour 5 minutes
8
Ingredients
- 2 pounds Brussels sprouts
- 1 tablespoon olive oil
- ¼ teaspoon kosher salt
- ⅛ teaspoon ground black pepper
- 2 tablespoons unsalted butter
- ½ cup diced yellow onion (about ½ medium onion)
- 2 tablespoons all-purpose flour
- 1 ¾ cups whole milk
- 1 teaspoon roughly chopped fresh thyme (or ½ teaspoon dried thyme)
- ¼ teaspoon freshly grated nutmeg
- 4 ounces Gruyère cheese, shredded and divided
Instructions
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To prepare Brussels sprouts, rinse them well under running water. Carefully trim off the tough bottom (stem) end and remove any brown or wilted outer leaves. Once cleaned, cut each Brussels sprout in half lengthwise from top to bottom.2 pounds Brussels sprouts
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Preheat your oven to 400ºF (200ºC). Prepare a 9×13-inch baking dish by spraying it generously with nonstick baking spray to prevent sticking.
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In a large bowl, combine the halved Brussels sprouts with the olive oil, kosher salt, and ground black pepper, tossing until the sprouts are evenly coated. Transfer them to the prepared baking dish and spread them in a single layer. Bake for 20 minutes, or until the sprouts are just tender-crisp and beginning to brown slightly on the edges. Remove the dish from the oven.1 tablespoon olive oil, ¼ teaspoon kosher salt, ⅛ teaspoon ground black pepper
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While the Brussels sprouts are roasting, prepare the cheese sauce. In a medium saucepan, melt the unsalted butter over medium heat. Add the diced yellow onion and sauté, stirring constantly, until it becomes translucent, which usually takes about 2 minutes. Stir in the all-purpose flour and continue to stir or whisk for 1 minute, cooking out the raw flour taste to create a roux.2 tablespoons unsalted butter, ½ cup diced yellow onion, 2 tablespoons all-purpose flour
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Slowly pour in the whole milk, whisking constantly to ensure no lumps form. Continue to cook over medium-low heat, stirring frequently, for 10 to 12 minutes, until the sauce thickens to a rich, creamy consistency. Remove the saucepan from the heat.1 ¾ cups whole milk
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Stir the fresh thyme and freshly grated nutmeg into the thickened sauce until well combined. Add half of the shredded Gruyère cheese to the sauce, stirring until it is completely melted and smooth. Pour this luscious cheese sauce over the roasted Brussels sprouts in the baking dish, stirring lightly to ensure all sprouts are coated. Sprinkle the remaining half of the shredded Gruyère cheese over the top of the gratin.1 teaspoon roughly chopped fresh thyme, ¼ teaspoon freshly grated nutmeg, 4 ounces Gruyère cheese, shredded and divided
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Return the baking dish to the preheated oven and bake for an additional 20 minutes, or until the top is beautifully golden brown, the cheese is bubbling, and the gratin is heated through.
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Allow the gratin to cool for 5 to 10 minutes before serving. This resting period allows the sauce to set slightly, making for easier and cleaner serving. Enjoy it straight from the baking dish!
Notes
- With bacon or pancetta: For an extra layer of savory flavor, add bacon or pancetta to the gratin. Dice 4-6 slices of bacon or pancetta into 1-inch pieces. Cook in a skillet until crisp, then drain well to remove excess fat. Stir the cooked bacon or pancetta into the cheese sauce along with the thyme and nutmeg before pouring it over the sprouts.
- Cheese variations: While Gruyère is highly recommended for its unique nutty flavor and excellent melting properties, other types of cheese can be successfully substituted. Consider using a good quality Swiss cheese, sharp cheddar, or a blend of Parmesan and Asiago for different flavor profiles.
- Make ahead tip: To prepare this dish in advance, you can trim and halve the Brussels sprouts up to two days ahead, storing them in a sealed container in the refrigerator. The onion can also be diced and stored similarly. Shred the Gruyère cheese up to a week in advance and keep it refrigerated, ready for assembly when you’re ready to bake.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.