Spaghetti Squash Lasagna Casserole

4.65 from 14 votes

Indulge in all the comforting flavors of lasagna without the guilt with this creamy Spaghetti Squash Lasagna Casserole. A perfect blend of hearty tomato sauce, creamy ricotta cheese, and tender strands of spaghetti squash, this vegetarian dish is a low-carb twist on a classic favorite.

Prep Time30

Cook Time1 20

Total Time1 50

Course: Entree

Cuisine: Italian

Servings:

Calories: 267kcal

Author: Dr. Sonali Ruder

Equipment

Large baking dish

Ingredients

1 large spaghetti squash (about 3 ½ pounds)
1 teaspoon olive oil
1 container (15 ounces) part-skim ricotta cheese
1 large egg
5 ounces frozen chopped spinach, defrosted and squeezed dry
1 ½ cups part-skim shredded mozzarella cheese, divided use
1 teaspoons salt
¼ teaspoon black pepper
1 jar (24 oz) jarred marinara sauce, like Rao's
⅓ cup grated Parmigiano-Reggiano cheese
fresh parsley or basil for garnish, optional

US Customary - Metric

Instructions

Preheat oven to 400°F. Cut the squash in half lengthwise and remove the seeds. Brush the flesh with 1 teaspoon oil. Place squash halves cut side down on a baking sheet lined with parchment paper. Roast in the oven until tender, about 40-45 minutes. Remove from oven and cool. When the squash is cooled, scrape the flesh with a fork so that it forms spaghetti-like strands. You should have a total of about 6 cups total. Alternatively, you can cook the spaghetti squash in the air fryer.
Mix the ricotta, egg, spinach, ½ cup mozzarella cheese, salt, and pepper together in a large bowl. Squeeze all of the liquid from the spaghetti squash and add it to the bowl (the squash releases a lot of water as it cooks so make sure to squeeze it well). Stir to combine all of the ingredients.
Turn the heat on the oven down to 375°F. To assemble the lasagna, spread a thin layer of tomato sauce on the bottom of an 8x11-inch baking dish. Next, spread half of the squash and ricotta mixture on top. Spread half of the remaining tomato sauce on top of the squash. Then, top with another layer of squash and another layer of tomato sauce. Finally, sprinkle the remaining 1 cup of mozzarella and the Parmigiano cheese on top.
Bake in the oven 35-40 minutes until bubbly and cheese is melted. Garnish with parsley. Let stand 10 minutes before cutting and serving.

Notes

I use spinach in the filling of this vegetarian spaghetti squash recipe but you can add other veggies like bell peppers or mushrooms for a meaty texture

If you are not trying to keep this dish vegetarian, you can add ground turkey, beef or Italian sausage to this spaghetti squash lasagna.

You can use your favorite jarred marinara sauce or make homemade tomato sauce, if you have more time.

Add your favorite seasonings to bump up the flavors in this dish like chili flakes, Italian seasoning or fresh herbs like parsley or basil.

Make this casserole ahead of time and refrigerate or freeze it for a convenient weeknight meal.

For more details on how to cook spaghetti squash, read my post on how to bake a whole spaghetti squash in the oven. To cook it in the air fryer, read my post on air fryer spaghetti squash.

Nutrition