Cheesy Spaghetti Squash Casserole (Vegetarian)

The aroma alone brings me back to crisp autumn evenings. Growing up, my mom would always make this cheesy spaghetti squash casserole after our first trip to the pumpkin patch. The combination of sweet squash, savory vegetables, and that bubbling, golden cheese crust… it was the ultimate comfort food. It was so hearty and satisfying, even my meat-loving dad never missed the meat. It’s a dish that truly feels like home.

Recipe Overview

• Prep Time: 25 minutes
• Cook Time: 45 minutes
• Total Time: 1 hour 10 minutes
• Servings: 6-8
• Dietary Type: Vegetarian

Ingredients

• 1 spaghetti squash
• 1 large onion, diced
• 1 green bell pepper, chopped
• 1 red bell pepper, chopped
• 2 tablespoons olive oil
• 1 (28 ounce) can crushed tomatoes
• 3-5 garlic cloves, minced
• 1 teaspoon basil
• ½ teaspoon oregano
• ½ teaspoon crushed red pepper flakes (optional)
• 1 cup grated mozzarella cheese
• ½ cup grated Parmesan cheese (use real Parmesan, not the powdery kind!)

Equipment Needed

• Microwave-safe dish
• Plastic wrap
• Large bowl
• Skillet
• 9×13 inch baking dish

Instructions

1. First, prepare the spaghetti squash. Cut the squash in half lengthwise and remove the seeds.

2. Place the squash, cut sides up, in a microwave-safe dish. Add about ¼ cup of water to the dish.

3. Cover the dish with plastic wrap and microwave on high for 10-12 minutes, or until the squash is tender. To check for doneness, pierce the squash with a fork; it should be easily pierced.

4. Let the squash sit, covered, for 5 minutes after microwaving. This will allow it to cool slightly and make it easier to handle.

5. Once cool enough to handle, use a fork to “comb” out the strands of spaghetti squash into a large bowl. Set aside.

6. Preheat your oven to 375 degrees Fahrenheit (190 degrees Celsius).

7. In a small bowl, mix together the mozzarella cheese and Parmesan cheese. Set aside.

8. Heat the olive oil in a skillet over medium heat.

9. Add the diced onion, green bell pepper, red bell pepper, and minced garlic to the skillet.

10. Sauté the vegetables over medium heat for about 5 minutes, or until the onion becomes translucent and the peppers soften slightly.

11. Add the can of crushed tomatoes and the crushed red pepper flakes (if using) to the skillet.

12. Simmer the sauce, uncovered, for about 15 minutes, stirring occasionally to prevent sticking. This allows the sauce to thicken and the flavors to meld together.

13. In the large bowl containing the cooked spaghetti squash, mix the squash well with the cooked vegetables and tomato sauce. Ensure that the squash is evenly coated with the sauce.

14. Pour half of the spaghetti squash mixture into a 9×13 inch baking dish.

15. Top the squash mixture with half of the cheese mixture.

16. Pour the remaining spaghetti squash mixture over the cheese.

17. Sprinkle the remaining cheese over the top of the squash.

18. Bake in the preheated oven for 30 minutes, or until the cheese is bubbly and slightly browned.

19. Let the casserole cool for 10-15 minutes before serving. This allows the casserole to set slightly, making it easier to serve.

Expert Tips & Tricks

• For a richer flavor, roast the spaghetti squash in the oven instead of microwaving it. Cut the squash in half, drizzle with olive oil, and roast cut-side down at 400 degrees Fahrenheit (200 degrees Celsius) for 40-45 minutes, or until tender.
• Don’t overcook the spaghetti squash; it should be tender but still have a bit of bite. Overcooked squash will be mushy.
• If you don’t have fresh garlic, you can use 1 teaspoon of garlic powder.
• For a spicier casserole, add more crushed red pepper flakes or a pinch of cayenne pepper.
• To prevent the cheese from browning too quickly, tent the casserole with aluminum foil during the last 10 minutes of baking.
• Make ahead: You can assemble the casserole ahead of time and store it in the refrigerator for up to 24 hours before baking. Add about 10-15 minutes to the baking time if baking from cold.
• If your sauce seems too watery after simmering, you can add a tablespoon of tomato paste to thicken it.

Serving & Storage Suggestions

This cheesy spaghetti squash casserole is delicious served as a main course or as a hearty side dish. Garnish with fresh basil or parsley for a pop of color. Leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days. To reheat, bake in a preheated oven at 350 degrees Fahrenheit (175 degrees Celsius) until heated through, or microwave in individual portions. The casserole can also be frozen for up to 2-3 months. Thaw completely in the refrigerator before reheating.

Nutritional Information

Nutrient	Amount per Serving	% Daily Value
Calories	212 kcal	–
Total Fat	11.8g	18%
Saturated Fat	4.7g	23%
Cholesterol	22.1mg	7%
Sodium	430.5mg	17%
Total Carbohydrate	18.9g	6%
Dietary Fiber	3.8g	15%
Sugars	2.7g	–
Protein	10.6g	21%

Variations & Substitutions

• Gluten-Free: This recipe is naturally gluten-free.
• Dairy-Free/Vegan: Substitute the mozzarella and Parmesan cheese with your favorite vegan cheese alternatives. Nutritional yeast can also be added for a cheesy flavor.
• Add Vegetables: Feel free to add other vegetables to the casserole, such as mushrooms, zucchini, or spinach.
• Spicy: For extra heat, add a pinch of cayenne pepper or a dash of your favorite hot sauce to the sauce.
• Herbs: Experiment with different herbs, such as thyme, rosemary, or Italian seasoning.
• Ricotta Cheese: You can add a layer of ricotta cheese (or dairy-free ricotta) for extra creaminess.

FAQs (Frequently Asked Questions)

Q: Can I use pre-shredded cheese?
A: While you can use pre-shredded cheese, freshly grated cheese melts more smoothly and has a better flavor.

Q: Can I freeze this casserole?
A: Yes, you can freeze the casserole for up to 2-3 months. Thaw it completely in the refrigerator before reheating.

Q: How do I prevent the spaghetti squash from becoming watery?
A: Don’t overcook the spaghetti squash. It should be tender but not mushy. Also, make sure to drain any excess water from the squash after cooking.

Q: Can I use a different type of squash?
A: While spaghetti squash is ideal for this recipe, you could also use butternut squash or acorn squash as alternatives, though the texture and flavor will be slightly different.

Q: Do I have to use crushed red pepper flakes?
A: No, the crushed red pepper flakes are optional. If you don’t like spice, you can omit them.

Final Thoughts

I truly hope you give this Cheesy Spaghetti Squash Casserole a try! It’s a versatile and comforting dish that’s perfect for any occasion. Feel free to adapt the recipe to your liking and add your own creative twists. And if you do make it, please share your feedback and let me know what you think. It would pair wonderfully with a crisp green salad and a glass of your favorite white wine. Happy cooking!