This creamy, comforting Instant Pot Spaghetti Squash Alfredo is an easy, plant-based weeknight favorite. It’s nutrient-dense, ready in about 30 minutes, and uses simple pantry ingredients and a pressure cooker to deliver tender, noodle-like squash strands tossed in a rich, dairy-free sauce.
Originally posted April 3, 2018; updated with new recipe details and photos.
Cooking spaghetti squash in the Instant Pot is fast and reliable: 10 minutes of high pressure softens the squash into strands that resemble pasta. The vegan Alfredo sauce here is earthy and savory, built from sautéed mushrooms and shallots, creamy unsweetened soy milk, arrowroot (or cornstarch) to thicken, nutritional yeast for a cheesy note, a squeeze of lemon for brightness, and a splash of white wine or vegetable stock to deepen the flavor.
This recipe is versatile: serve it simply for cozy comfort, or add mix-ins to suit your mood. Below you’ll find ingredient notes, step-by-step instructions for pressure cooking the squash and making the Alfredo, tips for the best results, variations, storage guidance, and common questions.
Ingredients
Spaghetti squash: Choose a medium squash (about 2–3 pounds) with firm, smooth skin. When cooked, the flesh pulls into long, noodle-like strands.
White wine or vegetable stock: White wine adds acidity and depth; substitute quality vegetable broth if you prefer.
Baby Bella mushrooms: Also called cremini, they bring umami and a meaty texture. Button mushrooms work too.
Non-dairy milk: Use plain, unsweetened soy milk for the creamiest sauce. Unsweetened almond or oat milk can substitute.
Arrowroot powder or cornstarch: A tablespoon thickens the sauce to a silky consistency.
Nutritional yeast: Adds a nutty, cheesy flavor without dairy.
Lemon juice: Fresh lemon brightens and balances the richness.
Seasonings: Onion powder, garlic powder, sea salt, black pepper, and red chili flakes. Fresh parsley for garnish.
How to Cook Spaghetti Squash in the Instant Pot
These steps make the process quick and fail‑safe.
- Prepare the squash. Cut the spaghetti squash lengthwise and scoop out the seeds with a spoon.
- Pressure cook. Place 1 cup of water and a steam rack in the Instant Pot, set the squash halves on the rack, seal the lid, and cook on HIGH for 10 minutes. Quick-release when time is up.
- Cool and shred. Let the squash rest until it’s cool enough to handle, about 10–20 minutes, then rake a fork through the flesh to form spaghetti-like strands.
- Prepare the sauce. Warm oil in a skillet over medium heat. Sauté minced shallots until tender, then add sliced mushrooms and a pinch of salt and cook until the mushrooms release their liquid and soften, about 6–8 minutes.
- Thicken the sauce. Whisk arrowroot (or cornstarch) into the non-dairy milk until smooth. Pour into the skillet with the mushrooms, then add nutritional yeast, vegetable stock or wine, garlic powder, onion powder, lemon juice, and salt. Simmer 3–5 minutes until the sauce thickens and becomes creamy.
- Combine. Toss the shredded spaghetti squash with the Alfredo sauce in the skillet. If the sauce is too thick, loosen it with a splash of non-dairy milk. Taste and adjust salt, pepper, or lemon juice as needed.
- Serve. Garnish with chopped parsley, black pepper, and red chili flakes for a touch of heat. Serve warm and enjoy.
Jenné’s Recipe Tips
- Use a sharp knife. A sturdy chef’s knife makes cutting the squash safer and easier.
- Cut lengthwise. Halving the squash lengthwise yields longer, spaghetti-like strands.
- Don’t overcook. Ten minutes under pressure produces tender strands without becoming mushy.
- Let it cool before shredding. Allowing a short rest helps the strands separate cleanly.
- Season the strands. Toss the cooked squash with a little olive oil, salt, and pepper before adding sauce to boost flavor.
- Use unsweetened milk. Plain, unsweetened plant milk keeps the sauce savory.
- Adjust sauce consistency. Add more soy milk to loosen or more arrowroot to thicken as needed.
Recipe Variation
Try these variations to change the flavor profile:
- Cheesy Alfredo: Stir in 1–2 tablespoons of cashew butter with the nutritional yeast for an ultra‑creamy, nutty sauce.
- Italian Meatball: Add vegan lentil meatballs and finish with fresh basil for a hearty meal.
- Primavera: Fold in sautéed asparagus, broccoli, zucchini, or cherry tomatoes for color and extra nutrition.
- Pesto Squash: Swap the Alfredo for your favorite vegan pesto for a bright, herb-forward dish.
Storage Directions
- Refrigerate: Store cooled leftovers in an airtight container for up to 3 days. Freezing is not recommended because the squash texture deteriorates when thawed.
- Reheat: Warm gently on the stovetop or in the microwave with a splash of non-dairy milk to restore creaminess.
Frequently Asked Questions
It’s done when the flesh is easily pierced with a fork at the deepest part.
Run a fork lengthwise through the cooked flesh; the strands will separate naturally into noodle-like pieces.
Cut the squash into quarters or cook the halves in batches. Never fill the pot past the manufacturer’s maximum fill line.
Yes. Bake at 375°F for about 45 minutes with a splash of water, or steam on the stovetop for roughly 20 minutes if you prefer not to use a pressure cooker.
Absolutely. Toss the shredded squash with olive oil, salt, pepper, and garlic powder for a simple side or base.
More Easy Instant Pot Recipes
- Instant Pot White Beans with Lemon and Rosemary
- Instant Pot Mexican Rice
- Instant Pot Whole Cauliflower Piccata
- Instant Pot Vegan Sausage Pasta
- Instant Pot Black Bean Soup
Instant Pot Spaghetti Squash
Ingredients
- 1 medium spaghetti squash (about 3.5 pounds)
- 1 tbsp extra virgin olive oil
- 2 medium shallots, minced
- 10 oz baby bella mushrooms, thinly sliced
- 1 cup plain unsweetened soy milk (or other unsweetened non-dairy milk)
- 1 tbsp arrowroot powder or cornstarch
- 1/4 cup vegetable stock (or 2 tsp vegetable bouillon dissolved in 1/4 cup hot water)
- 1/2 cup nutritional yeast
- 1 tsp onion powder
- 1/2 tsp garlic powder
- 1–2 tbsp fresh lemon juice
- 1 tsp sea salt, plus more to taste
Instructions
- Cut the spaghetti squash in half lengthwise and scoop out the seeds.
- Add 1 cup of water and a steam rack to the Instant Pot. Place the squash halves on the rack, seal the lid, and pressure cook on HIGH for 10 minutes.
- Quick-release the pressure when the cook time ends, then carefully remove the squash and let it cool for 10–15 minutes until safe to handle.
- Use a fork to pull the flesh into strands.
- Warm oil in a skillet over medium heat and sauté the shallots 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 with the arrowroot until smooth. Pour into the skillet with the mushrooms, then stir in the vegetable stock, nutritional yeast, garlic powder, onion powder, lemon juice, and salt. Simmer 3–5 minutes until thickened.
- Toss the spaghetti squash strands with the Alfredo sauce. Add a splash of non-dairy milk if the sauce is too thick. Adjust seasoning to taste.
- Garnish with red chili flakes, black pepper, and fresh parsley. Serve hot.
Notes
Storage Directions
- Refrigeration: Keep cooled leftovers in an airtight container for up to 3 days. Freezing is not recommended.
- Reheating: Gently reheat on the stovetop or microwave with a splash of non-dairy milk to loosen the sauce.
Recipe Pro-Tips
- Sharp knife: Use a sturdy chef’s knife to halve the squash safely.
- Lengthwise cuts: Yield longer strands that resemble spaghetti.
- Avoid overcooking: Ten minutes in the Instant Pot preserves a pleasant, slightly firm texture.
- Cool before shredding: Resting briefly helps the strands separate more cleanly.
- Season the strands: Toss cooked squash with olive oil, salt, and pepper before combining with sauce for better flavor.
- Unsweetened milk: Prevents a sweet off-note in the savory sauce.
- Adjust thickness: Add more non-dairy milk to thin or more arrowroot to thicken.
Nutrition