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.
Why you’ll love it: This recipe is pure comfort food: pasta, cheese, and spinach baked in a yummy casserole.
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
I just love this pasta bake! Baked spaghetti was always (and still is!) one of my favorite meals. My mom wisely made extra spaghetti when she cooked up a batch of homemade spaghetti sauce and saved the excess pasta to make this cheesy delight with a Florentine twist. I have to confess that I liked this better.
And what’s not to like? Pasta (which gets just a little bit crispy around the edges), lots of cheesy goodness, spinach and mushrooms, baked into a bubbling and golden brown casserole. I think you’ll love it, too!
About this Recipe
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.
I’ll run you through the recipe to get you started, with lots of extra tips and ideas.
You’ll find a printable recipe card with complete directions and nutrition information at the end of the post.
What you need
- Spaghetti: Choose your favorite brand. I like to use whole wheat spaghetti for this casserole. You’ll need 8 oz. (half of a pound box). 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 really enhance the flavor of the spinach and pasta.
- Spinach: Use a package of frozen chopped spinach, squeezed dry. If you’d rather use fresh spinach, check out the FAQs for how to do that.
- 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. I often substitute Swiss cheese because it goes well with the spinach and nutmeg.
- Nutmeg, Salt and Pepper: Easy seasonings from your spice cabinet. I usually use freshly grated nutmeg which is a bit more potent than ground nutmeg.
How to make it
Let’s get started! 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.
Get the oven preheating and find a 1 1/2 quart casserole or baking dish. Spray it with non-stick cooking spray.
Meanwhile, shred the cheese and prep the mushrooms, onions, and garlic. Heat up a skillet and do a quick sauté of the mushrooms, onions, and garlic.
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.
Put the whole business into the casserole dish you prepared.
Sprinkle with the reserved cheese and cover the dish.
Bake for twenty-five minutes, uncover, and bake 20 minutes more.
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 really complement this dish.
While there are some differences nutritionally, the advantages of fresh vs. frozen spinach pretty much balance each other out. It’s super convenient to keep frozen spinach in your freezer and it remains “fresh” while refrigerated spinach tends to lose nutrients each day it spends in the fridge.
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.
Besides making this yummy baked spaghetti, there are lots of ways to use plain leftover spaghetti. It can be refrigerated for three to five days, or frozen 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.
More ways to use leftover spaghetti: make an easy summer pasta salad with chicken; try a baked spaghetti pie (from Spends with Pennies); chop it into shorter lengths and add it to stir fries instead of rice, or add to chicken noodle soup.
That’s pretty much up to you! Use your favorite kind or what you happen to have. I like the Monterey Jack and Parmesan cheese in this recipe because it goes well with the spinach. Swiss cheese is great, too.
Make It Your Own
- Sauté a chopped bell pepper with the mushrooms and onions to add more veggies.
- Substitute whole wheat pasta especially if serving as a main dish. 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 cooked chicken for more protein, if desired.
- Don’t want to turn the oven on? Try this Instant Pot Lemon Pasta with Chicken. It’s a one pot pasta dish that is a crowd pleaser.
Make Ahead Ideas
Using leftover pasta is a big time saver. Buy pre-sliced mushrooms or prep them ahead of time. Thaw spinach in the fridge overnight.
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.
Storage & Reheating Suggestions
Leftover pasta bake can be refrigerated for three to five days. Cover well and refrigerate promptly. Freeze for up to 3 months, if desired.
To reheat, reheat in microwave in 30-second increments or until heated through.
- 8 oz. uncooked spaghetti
- 1 tablespoon olive oil
- 8 oz. sliced fresh mushrooms
- 1/2 medium yellow onion, finely chopped
- ½ teaspoon kosher salt
- ¼ teaspoon ground black pepper
- 1 clove garlic, minced
- 1 large egg, beaten
- 1 ½ cup 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 oz.) frozen chopped spinach, thawed and moisture squeezed out
- Cook pasta according to package directions. Drain; set aside.
- Preheat oven to 350°F and lightly grease (or spray with nonstick cooking spray) a 1 ½ quart casserole or baking dish.
- While pasta is cooking, heat oil in a skillet over medium high heat. Add mushrooms and onions, sprinkle with salt and pepper. Sauté for 6-7 minutes or until mushrooms are golden and onion is soft. Add garlic and cook, stirring, for 1 minute more. Remove from heat.
- Combine egg, 1 cup Monterey Jack cheese, sour cream, milk, 2 tablespoons Parmesan, pepper, and nutmeg in large bowl. Add spinach, mushroom mixture, and cooked spaghetti; mix well.
- Place in prepared casserole dish. Sprinkle with remaining Monterey Jack and Parmesan cheese.
- 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.
- If desired, substitute fresh spinach for frozen. One pound of spinach equals one 10-ounce box. Sauté fresh spinach until leaves have wilted.
- Any type of pasta can be substituted, including whole wheat.
- Casserole can be made ahead and refrigerated overnight or frozen. Bake as directed, adding 10 minutes to covered portion of baking time.
This website provides approximate nutrition information for convenience and as a courtesy only. Nutrition data is gathered primarily from the USDA Food Composition Database, whenever available, or otherwise other online calculators.