Spaghetti Squash Casserole

This spaghetti squash casserole pairs strands of tender spaghetti squash with vegetables and meat sauce to create a delicious, low-carb, high-protein meal that serves a crowd.

Whether you’re looking for a way to add more veggies to your diet or want a lighter alternative to pasta, spaghetti squash is a great option. Once baked, this hearty winter squash can be pulled into long pasta-like strands that are filling and full of nutrients.

The combination of baked spaghetti squash and hearty meat sauce, topped with a bit of mozzarella and parmesan, creates a cheesy spaghetti squash casserole that adults and kids of the family can agree on, and it makes great leftovers too!

Why You’ll Love It

• Low Carb – With 35 grams of carbohydrates and 9 grams of fiber per serving, this low-carb casserole is a veggie-filled meal.
• High Protein – The combination of ground beef, mozzarella, and parmesan ensures that this baked spaghetti squash casserole recipe contains over 25 grams of protein per serving.
• Feeds a Crowd – This recipe makes 6 servings and makes great leftovers too.
• Great for Meal Prep – This spaghetti squash casserole keeps well in the fridge and freezer so it’s great for make-ahead meals.

Ingredients and Substitutions

• Spaghetti Squash – To create a noodle-like base for the casserole, add some veggies and lots of fiber.
• Ground Beef – The recipe calls for ground beef, however, you can use ground bison, ground chicken, or ground turkey if preferred.
• Onion and Garlic – To add some flavor and fragrance to the dish. You can use onion powder and garlic powder if preferred, see the notes section of the recipe for details.
• Bell Pepper – To add some vegetables. The recipe calls for a red bell pepper, however, you can use any color you like or have on hand.
• Tomatoes – A mixture of canned tomatoes and tomato paste to make the meat sauce. The recipe calls for a can of crushed tomatoes, however, you can use a jar of tomato sauce or your favorite pasta sauce if you prefer.
• Herbs – A mix of dried basil, oregano, thyme, and red pepper flakes to make an Italian seasoning for the casserole.
• Mozzarella – To add some protein and a cheesy topping.
• Parmesan – To add some more protein and a bit of saltiness.
• Fresh Basil – To add some freshness and color, parsley also works well.
• Salt and Black Pepper – To season the casserole.

How to Make Spaghetti Squash Casserole

1. Cook spaghetti squash. Slice the spaghetti squash into rings, place them on a baking sheet, season them with a bit of salt, and bake them in the oven at 400°F for 40 minutes until tender.
2. Brown the beef. Warm the olive oil in a large pot, add the ground beef, and cook until lightly browned and no longer pink. Add onion, cook for 3-4 minutes until tender, then add garlic and cook for an additional until fragrant.
3. Make the meat sauce. Add the Italian seasonings, basil, oregano, thyme, red pepper flakes, salt, and black pepper, then add the crushed tomatoes and tomato paste and stir to combine. Reduce heat to a simmer and cook until the squash is baked.
4. Shred the baked spaghetti squash. Transfer the cooked spaghetti squash rings to a cutting board and, using a fork, pull the spaghetti squash flesh away from the skin to form strands.
5. Make the casserole. Transfer the shredded spaghetti squash strands to the meat sauce, stir to combine, then transfer the mixture to a baking dish, spreading it out evenly. Sprinkle the top with the shredded cheese.
6. Bake the casserole. Transfer the baking dish to the oven at 400°F and bake for 20 minutes until the cheese is melted, and the casserole is bubbling.
7. Serve and enjoy! Once baked, allow the spaghetti squash casserole to cool slightly, and serve it with a sprinkle of fresh basil on top.

You can find the detailed instructions in the recipe card below.

Expert Tips

Cut the spaghetti squash into rings. Although you can cut spaghetti squash lengthwise and roast the squash halves, cutting spaghetti squash into rings creates longer strands. Simply place the spaghetti squash on a cutting board horizontally, cut off and discard the stem, then slice the squash into 2-inch-thick rings and bake them in the oven until tender.

Use lean ground beef. Using lean ground beef in this recipe helps to ensure the casserole is not too oily or greasy. In addition to lean ground beef, you can use ground bison, ground turkey, or ground chicken.

Use store-bought sauce. If you want to save time or don’t have a pantry full of herbs and spices, you can use a large jar of your favorite tomato sauce instead of making your own. Just brown the beef and add the sauce to it.

Make it ahead of time. You can make this spaghetti squash casserole ahead of time and quickly reheat it before serving. Prepare the casserole fully as per directions and then reheat it in the oven at 350°F for 15-20 minutes until warmed through and the cheese is bubbly.

Serving Suggestions

This baked spaghetti squash casserole is a delicious low-carb and high-protein meal that can certainly be enjoyed on its own, but if you’re looking to stretch the meal into more portions or make it a little heartier, I suggest serving it with:

• Green salad
• Caesar salad
• Steamed broccoli
• Grilled zucchini
• Garlic bread
• Focaccia

More Casserole Recipes:

• Chicken Burrito Casserole
• Stuffed Pepper Casserole
• Butternut Squash Casserole
• Spinach Breakfast Casserole
• Sweet Potato Breakfast Casserole

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