Spaghetti Squash Casserole Recipe

This Spaghetti Squash Casserole with chicken and shredded cheese is the perfect weeknight meal. Made with roasted spaghetti squash, this casserole is easy to make, low carb, gluten-free, and I’ll bet that everyone in your family will be reaching for seconds!

Have you ever had spaghetti squash before? It’s when you roast up a nutritious and delicious winter squash and turn it into noodles so it can replace carb-heavy noodles. It’s one of my go-to low carb swaps and it can easily be turned into a full meal such as this spaghetti squash casserole.

For this recipe, we combine spaghetti squash with chicken and some sauce, top it with cheese, and bake to bring it all together. It quickly turns spaghetti squash from a side dish to the main star! One of my favourite things to do while cooking this spaghetti squash casserole is turning on the oven light and watching the cheese bubble up and melt all over.

This baked spaghetti squash casserole is fully of healthy goodness and thanks to the cheese, no one’s even going to miss the regular noodles or even realize they’re eating vegetables! What’s even better is that roasting one squash isn’t really much different than roasting two squashes. So if you like to make freezer meals to make dinner time easier later on, this recipe is perfect for doubling or even tripling.

If you are looking for more easy casserole recipes to make, my  Cauliflower Casserole RecipeSweet Potato Zucchini Casserole, and Broccoli and Cauliflower Casserole are all great choices to make this week for dinner!

close up of Spaghetti Squash Casserole with a spoon scooping

How to Make this Spaghetti Squash Casserole Recipe

Ingredients

  • Spaghetti squash — make sure the spaghetti squash you pick is firm and doesn’t have any cracks in them.
  • Olive oil
  • Salt and black pepper to taste
  • Olive oil
  • Red onions
  • Garlic cloves
  • Shredded chicken breast— or any boneless skinless shredded chicken you have on hand.
  • Store-bought spaghetti sauce — or try my homemade tomato sauce if you’ve got extra time!
  • Mozzarella — shredded

step by step instructional photos - roasting spaghetti squash and making the sauce

Instructions

Prep the Oven and Spaghetti Squash

  1. Preheat oven to 400F.
  2. Halve the spaghetti squash with a sharp knife and using a spoon, remove seeds before pouring olive oil on the inside of the spaghetti squash and season with salt and black pepper to taste.
  3. Place spaghetti squash cut-side down on the baking sheet and roast in oven on middle rack for about 40-50 minutes.
  4. Remove from oven and let cool slightly then using a fork, gently remove spaghetti squash strands from the squash and set aside.

Make the Sauce

  1. In a cast iron skillet 10”, heat olive oil over medium-high heat.
  2. Add onions and garlic and cook for about 3 minutes.
  3. Add cooked chicken and tomato sauce to the skillet, mix everything together to combine and cook for 1 minute. Add the spaghetti squash strands and mix all to combine.

Bake the Casserole

  1. In a casserole dish, place in the mixture of everything and top with mozzarella cheese. Bake for 10 minutes or until golden and bubbly.

step by step instructional photos - putting the spaghetti squash mixture into the baking pan, topping with cheese, and baking

Tips To Making This Spaghetti Squash Casserole

  • Make it Vegetarian: omit the cooked chicken or substitute with a vegetarian alternative to make the casseroles vegetarian.
  • The time it takes to roast your spaghetti squash depends on the size of it. To check if it’s done, run your fork through the squash. If the fork is able to pull the strands of “noodles” off the squash, then it’s ready. If not, let it continue to roast in the oven.
  • If you want to make the spaghetti squash in a different method, see my post on how to cook spaghetti squash on how to make it in the slow cooker or Instant Pot.
  • If you prefer the cheese to be a little bit more golden on the top, you can turn the broiler on high for a couple of minutes and broil it. Keep a close eye on it, as it can quickly go from golden brown to burnt!
  • Shred your own cheese! I know it can be a little bit of extra work but store-bought shredded cheese comes coated with a powder to prevent them from clumping, this can make the cheese grainy when melted. So shredding your own cheese gives you a smoother finish.

Leftover Storage & Freezing Tips

If you have leftovers, allow it to cool before wrapping or placing in an air tight container in the fridge for up to 5 days.

If you want to freeze this casserole, allow it to cool after baking then wrap it up tightly to avoid freezer burn and freeze for up to 3 months. When ready to eat, let thaw in the fridge overnight and then bake in the oven until it has heated through.

I recommend freezing it in an aluminum tray so you can heat it up directly in it without worrying about glass cracking.

close up of Spaghetti Squash Casserole

More Dinner Spaghetti Squash Recipes You May Enjoy

Spaghetti Squash Casserole Recipe

Yield: 6 people
Prep Time:
15 mins
Cook Time:
1 hr
Total Time:
1 hr 15 mins
This Spaghetti Squash Casserole with chicken and shredded cheese is the perfect weeknight meal. Made with roasted spaghetti squash, this casserole is easy to make, low carb, gluten-free, and I’ll bet that everyone in your family will be reaching for seconds!
Print Recipe
5 from 1 vote

Ingredients

For the Spaghetti Squash

For the sauce

  • 1 tbsp olive oil
  • ½ cup red onions — chopped
  • 2 garlic cloves — minced
  • 3 cups cooked shredded chicken breast— skinless
  • 1 cup store-bought spaghetti sauce — or homemade tomato sauce
  • 1 ½ cups shredded mozzarella

Instructions

For the Spaghetti Squash:

  1. Preheat oven to 400F.
  2. Halve the spaghetti squash with a sharp knife and using a spoon, remove seeds.
  3. Pour over olive oil on the inside of the spaghetti squash and season with salt and black pepper to taste.
  4. Place spaghetti squash cut-side down on the baking sheet and roast in oven on middle rack for about 40-50 minutes. The time will depend on the size of the spaghetti squash.
  5. Remove from oven and let cool slightly.
  6. Using a fork, gently remove spaghetti squash strands from the squash and set aside.

For the Sauce

  1. In a cast iron skillet 10”, heat olive oil over medium-high heat.
  2. Add onions and garlic and cook for about 3 minutes.
  3. Add cooked chicken and tomato sauce to the skillet, mix everything together to combine and cook for 1 minute. Add the spaghetti squash strands and mix all to combine.
  4. In a casserole dish, place the spaghetti squash/chicken/tomato sauce mixture and top with mozzarella cheese. Bake for 10 minutes or until golden and bubbly.
Course: dinner, Main Course
Cuisine: American
Keyword: casserole, Roasted Spaghetti Squash, Spaghetti Squash

Nutrition Information

Amount per serving (1/6) — Calories: 367, Fat: 17g, Saturated Fat: 7g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 7g, Cholesterol: 105mg, Sodium: 1218mg, Potassium: 406mg, Carbohydrates: 12g, Fiber: 4g, Sugar: 7g, Protein: 42g

If you make this recipe, follow @primaverakitchen on Instagram, snap a photo and hashtag it #primaverakitchen. I'd love to see what you're making!

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Spaghetti Squash Casserole