Instant Pot Spaghetti Squash w/ Creamy Alfredo Sauce (dairy-free)

This creamy and cozy Instant Pot Spaghetti Squash is the perfect plant-based comfort food. It’s nutrient-dense, quick to make, and incredibly satisfying. All you need is a handful of wholesome ingredients, a pressure cooker, 30 minutes, and this wholesome fall meal is all yours!

This post was originally published on April 3, 2018. It was updated with new recipe information and photos on Sept 17, 2025.

Spaghetti squash in the Instant Pot is the easiest way to enjoy this nourishing, low-carb vegetable. All it takes is 10 minutes of pressure cooking for the squash to transform into tender, noodle-like strands that pair beautifully with a rich, dairy-free Alfredo sauce. The homemade vegan Alfredo is made from mushrooms, nutritional yeast, fresh lemon juice, savory spices, protein-rich soy milk, and a hint of white wine to enhance the richness.

I love how versatile this dish is. It’s the perfect comfort food for busy weeknights, yet elegant enough to wow dinner party guests. Keep it simple and cozy on its own, or dress it up with additional mix-ins and toppings.

For more healthy, plant-based pasta recipes, try my Vegan Pasta Puttanesca, Vegan Butternut Squash Mac and Cheese, or Spinach Pesto Pasta.

Ingredients

Spaghetti squash: This versatile vegetable becomes “noodle-like” when cooked. Look for a medium squash (about 2-3 pounds) with a firm and smooth, deep-yellow skin.

White Wine: Adds depth and a nice acidic brightness to the rich sauce. Alternatively, use a high-quality vegetable broth or stock.

Baby Bella Mushrooms: Bring a rich umami flavor and meaty texture to the dish. Cremini or button mushrooms also work well.

Non-Dairy Milk: Use plain, unsweetened soy milk for the creamiest sauce. Almond or oat milk are great alternatives–just make sure to use unsweetened and plain to avoid changing the flavor.

Arrowroot Powder: Helps thicken the Alfredo sauce for the perfect silky, creamy texture. Alternatively, use cornstarch.

Nutritional Yeast: The secret to the cheesy, nutty Alfredo flavor without the dairy.

Lemon Juice: Freshly squeezed lemon juice adds brightness and balances the richness of the sauce, yum!

Seasonings: Onion powder, garlic powder, and sea salt build a deep savory flavor. Black pepper and red chili flakes add a little heat as toppings, and fresh parsley adds a burst of herbaceous freshness.

How to Cook Spaghetti Squash in the Instant Pot

I love how it’s ready in a handful of easy, anyone-can-do-it steps!

Prepare the squash. Cut the spaghetti squash in half lengthwise and use a spoon to scoop out the seeds.

Pressure cook. Add 1 cup of water and a steam grate to the Instant Pot. Place the squash halves inside, seal the lid, and pressure cook spaghetti squash on high for 10 minutes. Quick-release the pressure once done.

overhead of steam basket inside of the instant pot

Cool and shred. Let the squash cool slightly until cool enough to handle–about 20 minutes. Then use a fork to pull the strands into “spaghetti”.

Prepare the sauce. In a skillet, warm the oil on medium heat then add the shallots and sauté until tender. Add the mushrooms with a pinch of salt and cook until softened, about 8 minutes.

Thicken the sauce. Whisk the arrowroot into the non-dairy milk until smooth, then pour the mixture into the skillet. Stir in nutritional yeast, garlic powder, onion powder, broth, lemon juice, and salt. Simmer for a few minutes until thickened and creamy.

overhead soy milk and cornstarch in hand

Combine. Toss the spaghetti squash strands with the Alfredo sauce. If the sauce thickens too much, add a splash of non-dairy milk to loosen it.

Serve. Garnish with fresh parsley, black pepper, and red chili flakes for a little extra heat. Enjoy!

Jenné’s Recipe Tips

Use a sharp knife. I recommend a chef’s knife or another knife with an extended tang, allowing you to get good leverage while cutting the firm squash.
Cut the squash lengthwise for longer strands. This creates longer, spaghetti-like noodles that hold up better in the sauce.
Avoid overcooking the squash. Overcooking can create a mushy texture. Stick to 10 minutes in the Instant Pot for tender, spaghetti-like strands.
Cool the squash before shredding. The strands come out cleaner and firmer if you allow the squash to rest about 20 minutes after cooking.
Season the squash. Before mixing with the Alfredo, toss the cooked strands with a little olive oil, salt, and pepper to build flavor.
Use unsweetened milk. Choose a plain, unsweetened plant-based milk to keep the flavor savory.
Adjust the sauce thickness. Add more soy milk if needed after mixing in the squash. Add more arrowroot powder if the sauce is too thin.

Recipe Variation

Switch up the flavors to enjoy pressure cooker spaghetti squash multiple ways:

Cheesy Alfredo: Stir in 1-2 tablespoons of cashew butter along with the nutritional yeast to make the sauce even creamier and more decadent.
Italian Meatball: Add vegan lentil meatballs and top the pasta with fresh basil.
Primavera Squash: Add sautéed veggies like asparagus, broccoli, zucchini, or cherry tomatoes for extra nutrition and color.
Pesto Squash: Add a homemade pepita cilantro pesto or use your favorite store-bought vegan pesto instead of Alfredo.

Storage Directions

Refrigeration: Store cooled leftovers in an airtight container in the refrigerator for up to 3 days. I don’t recommend freezing—the squash’s texture breaks down upon thawing.
Reheating: Warm gently on the stovetop or in the microwave with a splash of non-dairy milk to keep the sauce creamy.

Frequently Asked Questions

How do I know when spaghetti squash is done?

Spaghetti squash is done when you can easily pierce the deepest part of the flesh with a fork.

What’s the best way to shred spaghetti squash into strands?

To easily shred spaghetti squash, run a fork lengthwise through the flesh, releasing the strands as you go.

What if the two spaghetti squash halves don’t fit in the Instant Pot?

If the squash halves don’t fit, cut them in half to create quarters or pressure cook the halves in batches, with the same amount of water for each batch. For safety, always be sure not to fill the Instant Pot beyond the maximum fill line.

Can I bake the squash?

If you don’t have or prefer to use the Instant Pot, bake the squash covered with a splash of water in a 375°F oven for 45 minutes or steam it in a pot fitted with a steamer basket on the stovetop for 20 minutes.

Can I make this without the sauce?

Certainly—for classic Instant Pot spaghetti squash, season the freshly shredded squash with olive oil, salt, pepper, and garlic powder before serving.

More Easy Instant Pot Recipes

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Cut the spaghetti squash in half lengthwise and scoop out the seeds with a spoon.
Add 1 cup of water and a steam grate to the Instant Pot. Place the squash halves inside, seal the lid, and pressure cook spaghetti squash on HIGH for 10 minutes.
Once done cooking, quick-release the pressure from the Instant Pot.
Carefully remove the spaghetti squash from the Instant Pot. Let it cool at room temperature for 10-15 minutes or until cool enough to safely handle.
Use a fork to pull or shred the strands into spaghetti-like pieces.
Warm oil in the skillet on medium heat, and add the shallots. Sauté until tender. Add the mushrooms with a pinch of salt and cook until softened, about 8 minutes.
In a small bowl, whisk the non-dairy milk and arrowroot until well combined. Pour the mixture into the skillet along with the vegetable stock, nutritional yeast, garlic powder, onion powder, lemon juice, and salt. Bring to a simmer and cook for 3-5 minutes until thickened and creamy.
Toss the spaghetti squash strands with the Alfredo sauce. If the sauce thickens too much, add a splash of non-dairy milk to loosen it. Season the sauce to taste with salt, pepper, and/or lemon juice.
Garnish the spaghetti squash with red chili flakes, black pepper, and fresh parsley and enjoy hot!

Storage Directions

Refrigeration: Store cooled leftovers in an airtight container in the refrigerator for up to 3 days. I don’t recommend freezing—the squash’s texture breaks down upon thawing.
Reheating: Warm gently on the stovetop or in the microwave with a splash of non-dairy milk to keep the sauce creamy.

Recipe Pro-Tips

Use a sharp knife. I recommend a chef’s knife or another knife with an extended tang, allowing you to get good leverage while cutting the firm squash.
Cut the squash lengthwise for longer strands. This creates longer, spaghetti-like noodles that hold up better in the sauce.
Avoid overcooking the squash. Overcooking can create a mushy texture. Stick to 10 minutes in the Instant Pot for tender, spaghetti-like strands.
Cool the squash before shredding. The strands come out cleaner and firmer if you allow the squash to rest for a few minutes after cooking.
Season the squash. Before mixing with the Alfredo, toss the cooked strands with a little olive oil, salt, and pepper to build flavor.
Use unsweetened milk. Choose a plain, unsweetened plant-based milk to keep the flavor savory.
Adjust the sauce thickness. Add more soy milk if needed after mixing in the squash. Add more arrowroot powder if the sauce is too thin.

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