Spaghetti Squash Casserole


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Move over pasta casserole, spaghetti squash has a new place at the dinner table in this cheesy, saucy Spaghetti Squash Casserole. You get all the flavors of lasagna with far less work. The secret to the best texture is to bake this casserole on a sheet pan. You’ll get maximum crispy edges and melty cheese in every bite. 

overhead image of spaghetti squash casserole on a sheet pan

If you’re looking for a gluten-free or low carb spaghetti squash recipe, look no further than this casserole. This is one of those totally cozy recipes that just happens to be packed full of veggies. The squash is coated in sauce and mixed with cheese and doesn’t feel like it’s a sad substitute for pasta. It’s just good all on its own. Whether you love spaghetti squash or are just looking for a fresh alternative to pasta casserole, this recipe is for you. 

And letting the spaghetti squash just be squash instead of trying to make it a stand-in for pasta is when I think this variety of squash really shines. It’s exactly why Spaghetti Squash Egg Nests have become a staple make-ahead breakfast in my household.

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a roasted spaghetti squash cut in half and resting on a grey countertop

How to Make Spaghetti Squash Casserole

  1. Cook the squash. See below for two options, depending on how much time you have.
  2. Scrape out the squash strands and combine them with marinara sauce and provolone or mozzarella cheese.
  3. Spread the squash mixture out on a large rimmed baking sheet. You’ll want it in a thin layer for maximum crispy bits. 
  4. Top the casserole with ricotta and parmesan cheeses.
  5. Broil until golden brown and crisp in spots. 
  6. Top with chopped basil and serve warm.

Cook the Spaghetti Squash – 5 ways

  1. Slice in half first. This speeds up the process. Be sure to slice the squash through the more narrow, flesh side. It can be hard to slice it stem-to-stem. Roast at 400°F for 25 to 30 minutes.
  2. Roast the squash whole. This saves you the slicing step but takes more time. Just pierce it a few times with a knife and roast in a baking dish at 400°F for 50 to 60 minutes.
  3. Slow Cooker, Instant Pot, or Microwave – these all work too! For instructions read this post on other ways to cook spaghetti squash.
overhead image of ingredients for spaghetti squash casserole on a grey countertop

Recipe Tips and Tricks

  • Use good marinara sauce – The main flavor in this dish is the marinara, so use a favorite. I love the spicy Calabrian sauce from Trader Joe’s in this, but Rao’s is always good if you don’t want the spice. 
  • Don’t overcook the squash – You don’t want mushy strands of spaghetti squash, so check your squash as it cooks. Remove it when the sides start to cave in.
  • Don’t skip the basil – While this recipe is good even without it, that fresh basil on top really gives it the flavors of lasagna and brings it all together.


  • Add meat – This is great with cooked Italian sausage or ground beef. Or make a bolognese sauce or ragu sauce
  • Add more veggies – Try this with chopped sauteed baby spinach, diced red pepper, or add some basil pesto on top. 
  • Mix up the cheese – Any melty cheese can stand in for the mozzarella or provolone. Fontina and Swiss are great creamy cheeses that melt fast, but Gruyere would add a pleasant nutty flavor. 
  • Make it spicy – As I mentioned, I love to use a spicy marinara sauce in this recipe, but you could also just use regular marinara and add some red pepper flakes for a little heat. 
  • Add Italian seasoning – Taste your marinara and if it tastes like plain tomato sauce, try stirring in a little bit of Italian seasoning to amp up the flavor.

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overhead image of uncooked spaghetti squash casserole on a sheet pan


What is the best method for cooking spaghetti squash?

There is no right way to cook spaghetti squash. Because it has a very mild flavor and can be roasted inside the shell, just choose the method that is easiest for you. Roasting it halved or whole, cooking it in the microwave, using a crockpot or Instant Pot will all work well and give you great results. For the details on all of these methods, check out my guide to cooking spaghetti squash

Can spaghetti squash casserole be frozen?

I don’t recommend it. The cheese can separate and lead to a less-than-desirable texture. However, cooked spaghetti squash strands freeze well, and once you have those prepped, the rest of the dish comes together super fast.

What should I serve with spaghetti squash casserole?

Because it’s already packed with vegetables, you could serve it with bread – Italian-inspired focaccia would be great here. But a salad would be a great option as well. I love this with a classic Italian House Salad

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Spaghetti Squash Casserole

With all of the flavors of a classic lasagna, this casserole is actually packed with vegetables thanks to a base of spaghetti squash. You can bake this in almost any dish, but I love to spread it out on a sheet pan and broil it so that there are tons of crispy bits around the edges and on the top.
Prep: 10 minutes
Cook: 45 minutes
Total: 55 minutes
Servings: 4


  • Half Sheet Pan


  • 1 medium spaghetti squash (2 ½ to 3 pounds)
  • 1 tablespoon olive oil
  • 1 1/2 cups marinara sauce, plus extra for serving if you’d like
  • 1 cup grated provolone or mozzarella cheese
  • 1 cup whole milk ricotta cheese
  • 1/2 cup grated parmesan cheese
  • black pepper
  • fresh basil leaves, for topping


  • Preheat the oven to 400°F.
  • Spray a rimmed baking sheet with nonstick cooking spray or brush it with cooking oil.
  • Roast the squash in one of two ways. First, you can slice it in half through the flesh (not stem-to-stem). Place the squash cut-side down on a rimmed baking sheet and roast until tender, 25 to 30 minutes. OR, if you prefer not to mess with slicing through the raw squash and have a bit more time, just pierce the whole squash 10 times all over with a fork. Place it on a rimmed baking sheet and roast the entire squash until tender, 50 to 60 minutes.
  • Let the squash cool until you can safely handle it. While the squash cools, carefully move an oven rack so that it is about 8 inches below the heat source. Turn on the oven’s broiler.
  • If not sliced, slice the squash in half through the peel (not stem-to-stem). Scrape out and discard the seeds (or roast them separately like you would pumpkin seeds). Use a fork to scrape out the strands of squash. Combine them with marinara and provolone or mozzarella cheese.
  • Spread the squash out in a thin layer on the prepared baking sheet. Use a spoon to scoop and drop ricotta cheese all over the surface of the squash in roughly 1 tablespoon portions. Scatter the parmesan cheese over the entire dish.
  • Broil the squash until crisp and golden in places all over the top and sides, 6 to 8 minutes (keep a close eye on it since the intensity of broilers can vary).
  • Top the casserole with black pepper and fresh basil leaves. Slice into squares and serve warm, with warm marinara on the side if you’d like it a bit more saucy.


Calories: 373kcal | Carbohydrates: 26g | Protein: 22g | Fat: 22g | Saturated Fat: 13g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 6g | Cholesterol: 65mg | Sodium: 987mg | Potassium: 667mg | Fiber: 5g | Sugar: 10g | Vitamin A: 1362IU | Vitamin C: 12mg | Calcium: 557mg | Iron: 2mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Author: Jess Smith via Inquiring Chef
Cost: $8.00
Calories: 373
Keyword: healthyish, sheet pan recipe, spaghetti squash, squash, vegetarian, vegetarian casserole
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About Jess Smith

Jess is the recipe creator and photographer at She spent nearly a decade as the Chief Recipe Developer for the award-winning meal planning app Cook Smarts. Her colorful, healthyish recipes have been featured in popular online publications including Parade, Hallmark, and HuffPost.

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