Baked Spaghetti, served with Spinach

At a glance

What stands out: Rich baked spaghetti with spinach boasts two types of cheese and earthy mushrooms. It’s such a satisfying meal and can be made ahead if you like. This casserole recipe is pure comfort food!

How long it takes: 25 minutes to prep, and 45 minutes in the oven
Equipment you’ll need: pasta pan, strainer, baking dish, skillet, mixing bowl, oven
Servings: 4

Baked Spaghetti With Spinach

We just love this pasta bake! Baked spaghetti was always (and still is!) one of our favorite meals. Our mom wisely made extra spaghetti when she cooked up a batch of from-scratch spaghetti sauce and saved the excess pasta to make this cheesy delight with a Florentine twist.

And what’s not to like? The pasta gets just a little bit crispy around the edges, and there’s lots of cheesy goodness, spinach and mushrooms baked into a bubbling and golden brown casserole. We think you’ll love it, too!

Baked spaghetti is comfort food, plain and simple. It can be a satisfying meatless main dish or a filling side dish. This recipe is not difficult to make, especially if you have leftover pasta. (Be sure to check out our chicken tetrazzini recipe, too!)

What goes in

• Spaghetti: Choose your favorite brand. We like to use whole wheat spaghetti for this casserole. You’ll need about 8 ounces. It’s also a great way to use leftover spaghetti. If you want to use different pasta shapes, most will work in this recipe.
• Mushrooms: Regular white button mushrooms are fine. Buy already sliced mushrooms to save time.
• Onion and Garlic: Nothing fancy here, just plain cooking onions and garlic. They enhance the flavor of the spinach and pasta.
• Spinach: Use a package of frozen chopped spinach, squeezed dry.
• Egg, Sour Cream, Milk: This trio binds the elements of the casserole together.
• Monterey Jack Cheese and Parmesan Cheese: Other types of cheese are fine, too. We often substitute Swiss cheese because it goes well with the spinach and nutmeg.
• Nutmeg, Salt and Pepper: These are straightforward seasonings from your spice cabinet. We usually use freshly grated nutmeg which is a bit more potent than ground nutmeg.

Using Fresh Spinach

To substitute fresh spinach for frozen, use one pound of washed fresh spinach for a 10 ounce package of frozen. Remove any large stems, chop roughly, and place in a large skillet. Heat over medium high heat, cooking and stirring for three to four minutes, or until the leaves are wilted. If your spinach was completely dry before adding it to the pan, add a tablespoon or two of water so the spinach doesn’t burn. Cool and drain well, pressing out extra liquid.

How it comes together

Cook the pasta. Put a pot of water on the stove to heat up. Once it comes to boil, cook the spaghetti as directed on the package. Of course, if you’re using leftover pasta, you can just skip this step.

While the pasta is cooking, get the oven preheating and find a 1 ½ quart casserole or baking dish. Spray it with non-stick cooking spray.

Sauté the veggies. Meanwhile, shred the cheese and prep the mushrooms, onions, and garlic. Heat up a skillet and do a speedy sauté of the mushrooms, onions, and garlic.

Combine ingredients. You’ll need a large bowl to stir everything together. Before you add anything else to the bowl, lightly whisk the egg.

Add the milk and sour cream and blend it all together. Add the seasoning and most of the cheese (reserve some to sprinkle on top). Mix everything up well.

Add the pasta, sautéed veggies, and spinach, and stir it up. Make sure you scoop from the bottom as you stir so you get all the cheesy goodness thoroughly mixed in.

Arrange in baking dish. Put the whole business into the casserole dish you prepared.

Sprinkle with the reserved cheese and cover the dish.

Bake. Bake for twenty-five minutes, uncover, and bake 20 minutes more.

Serve. Serve the spaghetti casserole immediately or wait fifteen minutes or so. It’s so good either way. Because this is a pretty rich casserole, it’s best with a crisp arugula salad or citrus salad.

Wine Pairing

Try an Chardonnay aged in oak. The buttery flavor goes so well with the cheese, nutmeg, and spinach. Another good choice is a Pinot Noir. The crisp berry notes and acidity complement this dish.

Ways to change it

• More veggies! Sauté a chopped bell pepper with the mushrooms and onions.
• Substitute whole wheat pasta especially if serving the baked spaghetti as a vegetarian main dish. Whole wheat pasta is more nutritious. Other types of pasta are good, too.
• Try different combinations of cheese. Cottage cheese and ricotta are both good substitutes for the sour cream.
• Add meat. Cooked chicken can be added for more protein, if desired.
• Don’t want to turn the oven on? Try creamy chicken spinach pasta (it’s a one pot pasta recipe!) or Instant Pot lemon pasta with chicken.

How To Use Leftover Spaghetti

If you have leftover spaghetti or any other extra cooked pasta, don’t discard it! There are many ways to re-purpose plain cooked pasta, like this baked spaghetti recipe or our straightforward pizza baked pasta. Use leftover spaghetti to make a straightforward summer pasta salad with chicken, chop it into shorter lengths and add it to stir fries instead of rice, or add it to chicken noodle soup instead of noodles.

To store: Refrigerate leftover plain spaghetti for three to five days, or freeze in resealable freezer bags for a month. To refresh, bring a pot of water to a boil and submerge cooked spaghetti for a minute or two. Drain and serve immediately with your favorite sauce or turn it into another memorable main dish.

Make Ahead Ideas

Get a head start. Using leftover pasta is a big time saver. Buy pre-sliced mushrooms or prep them ahead of time. Thaw spinach in the fridge overnight.

Make it ahead. This casserole can be made completely ahead of time and refrigerated or frozen unbaked. If frozen, thaw overnight in the fridge before baking. Bake as directed, except increase first segment (covered) by ten minutes. Internal temp (check with instant read thermometer in center of casserole) should be 165°F.

Keeping leftovers

Refrigerate/Freeze: Leftover pasta bake can be refrigerated for three to five days. Cover well and refrigerate promptly. Freeze for up to 3 months, if desired.

Reheat: Leftover baked spaghetti can be microwaved in 30-second increments or until heated through.

Free Meal Plan

Interested in a weekly meal plan that includes this recipe? Take a look at Meal Plan #53. You’ll find a wholesome recipe for each weekday plus a categorized grocery list.

Browse Meal Plans

• Yield: 4
• Prep: 25 minutes
• Cook: 45 minutes
• Total: 1 hour 10 minutes

Ingredients

• 8 ounces uncooked spaghetti (see note)
• 1 tablespoon olive oil
• 8 ounces sliced fresh mushrooms
• ½ medium yellow onion (finely chopped)
• ½ teaspoon kosher salt
• ¼ teaspoon ground black pepper
• 1 clove garlic, minced
• 1 large egg
• 1 ½ cups shredded Monterey Jack cheese (divided)
• ½ cup sour cream
• ¼ cup milk
• 4 tablespoons grated Parmesan cheese (divided)
• ⅛ teaspoon ground nutmeg
• 1 package (10 ounces) frozen chopped spinach (thawed and moisture squeezed out)

Method

1. Cook pasta according to package directions. Drain; set aside.
2. Preheat oven to 350°F and lightly grease (or spray with nonstick cooking spray) a 1 ½ quart casserole or baking dish.
3. While pasta is cooking, heat oil in a skillet over medium high heat. Add mushrooms and onions, sprinkle with salt and pepper. Sauté for 6 to 7 minutes or until mushrooms are golden and onion is soft. Add garlic and cook, stirring, for 1 minute more. Remove from heat.
4. In a large bowl, lightly beat the egg. Add 1 cup Monterey Jack cheese, sour cream, milk, 2 tablespoons Parmesan, pepper, and nutmeg; stir to combine. Add spinach, mushroom mixture, and cooked spaghetti; mix well.
5. Place in prepared casserole dish. Sprinkle with remaining Monterey Jack and Parmesan cheese.
6. Bake, covered, for 25 minutes; remove cover and bake for another 20 minutes or until bubbling and golden brown. If desired, check internal temperature with instant read thermometer inserted in center of casserole; it should read 165 ° F.
7. Serve warm.

Notes

Using fresh spinach: If desired, substitute fresh spinach for frozen. One pound of spinach equals one 10-ounce box. S auté fresh spinach until leaves have wilted.

Pasta: Any type of pasta can be substituted, including whole wheat. You can also use leftover cooked pasta.

Make ahead: Casserole can be made ahead and refrigerated overnight or frozen. Bake as directed, adding 10 minutes to covered portion of baking time.