There is something incredibly satisfying about a comforting casserole that’s vibrant, flavorful, and fuss-free. This Instant Pot Spaghetti Squash Casserole Recipe is just that—a delightful way to transform humble spaghetti squash into a creamy, garlicky, and cheesy masterpiece in no time. The magic lies in how the Instant Pot cooks the squash perfectly tender, while the simple mixture of butter, garlic, Parmesan, and fresh parsley brings a rich and fresh flavor combo that makes every bite a treat. Whether you’re on the lookout for a healthy weeknight dinner or a unique side dish to impress guests, this recipe is a total winner that you’ll find yourself making again and again.

Ingredients You’ll Need

The image shows two halves of a yellow spaghetti squash placed inside a shiny metal pot with a built-in strainer. The squash halves are bright yellow with smooth textures and some stringy flesh inside the hollow center. The pot is black on the outside with handles on either side, resting on a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

This Instant Pot Spaghetti Squash Casserole Recipe relies on a handful of straightforward ingredients, each carefully chosen to balance texture and flavor beautifully. From the subtly sweet and tender squash to the bit of heat from red pepper flakes and the fresh brightness of parsley, every element works together to build a casserole that’s simple yet unforgettable.

1 2 pounds spaghetti squash: The star ingredient providing a naturally noodle-like texture perfect for a healthy casserole base.
1 cup water: Essential for steaming the squash in the Instant Pot to achieve that perfect tenderness.
2 tbsp butter: Adds luscious richness and helps carry the flavors of garlic and cheese throughout.
1 tbsp olive oil: Helps to gently sauté the garlic and red pepper flakes, layering in a subtle fruity note.
3 garlic cloves, minced: Brings a fragrant punch that livens up the dish with every bite.
¼ tsp red pepper flakes: A little spark of heat that enhances the flavor without overpowering the squash’s sweetness.
2/3 cup finely grated Parmesan cheese: Offers a nutty, savory depth and creamy texture when melted.
½ cup fresh parsley, chopped: Provides a fresh, herby burst of color and flavor to keep things bright.
Salt and black pepper to taste: The final seasoning touch to round everything out perfectly.

How to Make Instant Pot Spaghetti Squash Casserole Recipe

Step 1: Prepare the Spaghetti Squash

Start by cutting your spaghetti squash lengthwise and scooping out the seeds and ribbing—that fibrous center that can be discarded. This preps the squash for steaming and makes sure the strands cook evenly inside the Instant Pot.

Step 2: Steam the Squash in the Instant Pot

Place the metal trivet inside your Instant Pot and pour in 1 cup of water. Set the squash halves, cut side up, on the trivet. Seal the lid properly, switch the vent to sealing, and pressure cook on high for 7 minutes. When the timer beeps, perform a quick release to vent the steam.

Step 3: Cool and Scrape Out the Squash

Carefully remove the squash and let it cool for 15 to 20 minutes—this allows it to finish cooking and makes it easier to handle. Once cooled, use a fork to rake out the tender spaghetti-like strands into a bowl. These strands are what create the perfect casserole texture.

Step 4: Sautee Garlic and Red Pepper Flakes

Clean and dry the Instant Pot insert, then place it back inside the cooker. Hit the saute button and wait for it to show “HOT.” Add the olive oil and butter, letting the butter melt fully before tossing in the minced garlic and red pepper flakes. Cook for about 30 seconds until the garlic is fragrant and beautifully soft but not browned.

Step 5: Combine and Finish the Casserole

Add the spaghetti squash strands right into the sizzling garlic butter mixture. Toss everything well to coat the squash with aromatic flavor. Then, cancel the saute function and sprinkle in the freshly grated Parmesan cheese and chopped parsley. Give it another gentle toss, and season to taste with salt and black pepper. Serve this warm comforting casserole immediately for the best experience.

How to Serve Instant Pot Spaghetti Squash Casserole Recipe

Inside a black pot, there is a base layer of yellow shredded spaghetti squash that fills most of the pot, topped with a thick layer of white shredded cheese scattered unevenly across the surface. On top of the cheese in the center, there is a small cluster of finely chopped green herbs. A wooden spoon with a smooth, pale handle rests inside the pot, partly pushed into the layers. The pot is placed on a wooden surface with two small round bowls nearby containing white salt and black pepper. photo taken with an iphone --ar 4:5 --v 7

Garnishes

Elevate your Instant Pot Spaghetti Squash Casserole Recipe by adding colorful garnishes like extra parmesan shavings, a sprinkle of toasted pine nuts for crunch, or a few fresh basil leaves to brighten the aroma just before serving. A drizzle of high-quality extra virgin olive oil can also add a silky finish.

Side Dishes

This casserole pairs wonderfully with protein-focused sides such as grilled chicken, pan-seared salmon, or even roasted chickpeas for a vegetarian boost. A fresh green salad dressed in lemon vinaigrette or roasted seasonal vegetables will complement the creamy, cheesy texture beautifully.

Creative Ways to Present

For a fun twist, try serving the casserole inside the spaghetti squash shells for a rustic and charming look that’s perfect for a dinner party. You can also layer it with marinara and mozzarella to turn it into a low-carb lasagna-inspired dish that’s sure to wow your guests.

Make Ahead and Storage

Storing Leftovers

Leftover Instant Pot Spaghetti Squash Casserole Recipe can be stored in an airtight container and refrigerated for up to 3 days. The flavors meld nicely overnight, making it an easy and delicious next-day meal option.

Freezing

You can freeze this casserole if you want to save it for longer. Place portions in freezer-safe containers or bags and store for up to 2 months. To avoid sogginess, thaw overnight in the fridge before reheating.

Reheating

Reheat leftovers gently on the stove over medium-low heat or in the microwave until warmed through. Adding a splash of water or broth during reheating helps maintain moisture, keeping the casserole tender and delicious.

FAQs

Can I use a different type of squash for this Instant Pot Spaghetti Squash Casserole Recipe?

While spaghetti squash has a unique stringy texture that mimics noodles, you can experiment with other firm squashes like delicata or butternut, but keep in mind the texture and flavor will be different and may alter the dish’s character.

Is this recipe suitable for a low-carb diet?

Yes! Spaghetti squash is a popular low-carb alternative to traditional pasta, so this casserole fits perfectly into low-carb or keto-friendly meal plans.

Can I add other vegetables to the casserole?

Absolutely! Sautéed mushrooms, spinach, or roasted bell peppers would be fantastic add-ins. Simply toss them in during the saute step or mix them into the casserole before serving.

What can I use instead of Parmesan cheese?

If you’re looking for a dairy-free option, nutritional yeast can provide a similar cheesy flavor. Alternatively, Pecorino Romano works great if you want a sharper taste.

How do I know when the squash is perfectly cooked in the Instant Pot?

The instant pot cooks spaghetti squash in just 7 minutes on high pressure, which usually yields tender strands. After steaming, allow it to cool slightly, then scrape the flesh; it should pull apart easily without being mushy.

Final Thoughts

This Instant Pot Spaghetti Squash Casserole Recipe is the kind of dish that becomes a staple in your kitchen thanks to its simplicity, incredible flavor, and wholesome appeal. It proves that healthy eating can be exciting and comforting all at once. I encourage you to give it a try soon—once you do, it will likely become one of your favorite go-to recipes when you want something quick, tasty, and totally satisfying.