Turn on Saute mode and heat the Instant Pot. Add 2 tablespoons olive oil and sliced mushrooms along with a pinch of salt. Brown the mushrooms for 5 minutes, or until the mushrooms turn brown.
Remove the mushrooms to a plate and keep aside for later.
Add the remaining 1 tablespoon olive oil. Add chopped onion, garlic and saute for 2 minutes, until the onions begin to soften.
Add water, salt and pepper, and stir well. Add pasta and push it under the liquid. Turn off saute.
Close the lid and pressure cook on Manual or Pressure Cook for 5 minutes. Once the cooking time is up, perform a quick release of pressure. Open the lid after the pin drops.
Turn on Saute mode. Stir in heavy whipping cream. Now, add grated parmesan cheese and stir until well combined.
Stir in cooked peas, reserved sautéed mushrooms and simmer for 2-3 minutes. Adjust seasoning and add more salt or pepper as needed. Cancel saute.
Garnish with hand-torn basil leaves and serve with some more grated parmesan cheese.
Brown, then remove the mushrooms before pressure cooking. This keeps the integrity of the mushrooms intact and prevents them from overcooking.
Pasta cooking times will vary by shape and brand. Look to the package directions for proper cooking times. Then, for tender pasta, simply divide the lower number on the box in half. For al dente, subtract one more minute from the halved number.
Buy a whole block of cheese and grate it at home. The Parmesan cheese is meant for flavor, but also to thicken the sauce. But pre-shredded cheese has added starch or additives. Always look for the whole block of cheese with the rind and grate at home. It makes a world of difference in flavor and texture. Pecorino Romano is another great option.
Add chicken or shrimp for more protein. Top it off with sliced or grilled chicken. Or, add raw chicken cut in ½-inch pieces along with the pasta and pressure cook. For shrimp, season with salt and pepper and place in a skillet over medium heat until pink and opaque, about 4 to 5 minutes total.
Make it Gluten-Free or Vegan. Substitute the pasta with a certified gluten-free pasta. To make it vegan, replace the heavy cream with cashew cream and use a grated Vegan cheese.
Add some spice. Stir in ¼ teaspoon red pepper flakes along with the salt and pepper.
Store in the fridge for up to 4 days. The pasta will keep best in an airtight container. When ready to reheat, add 1-2 Tablespoons water or cream to prevent the pasta from drying out (the pasta soaks up sauce over time). Tent in a microwave-safe bowl with paper towel and reheat in 30-second increments in the microwave until warmed through.
Note: The nutrition facts below are my estimates. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.