Turn the Instant Pot on Saute normal mode and heat oil. Add the mushrooms, salt, pepper and give a quick stir. Add 2 tablespoons of water, mix well and cook covered with a non locking lid for 2 to 3 minutes. Take half of the mushrooms out and reserve. Move the remaining mushrooms on one side of the pot and add to the empty surface. Add garlic to the oil and cook it for a minute as it starts to release the aromas.
Add ¼ cup of vegetable broth and mix well, deglazing and removing any browning on the bottom of the pot.
Add remaining broth, break the spaghetti in half and start layering in a criss cross pattern. This is an important step as it prevents the spaghetti from sticking to each other.
Gently press the noodles so they are under the liquids. Do not mix. Layer the reserved mushrooms on top. Close the Instant Pot and pressure cook for 4 minutes followed by quick release.
Sprinkle cheese on top and garnish with parsley. Enjoy hot
Criss-cross the spaghetti noodles in the Instant Pot. This will prevent them from sticking together.
Completely submerge the noodles in the broth. Do not mix it, but make sure all the noodles are under the broth so they can cook completely.
Deglaze the pot with the vegetable broth and remove any browned bits. This will help the Instant Pot come to pressure and also prevent the "BURN" signal.
Adjust pressure cook time based on the pasta you use. If the package says 8 minutes, pressure cook for 4 mins for well-cooked pasta or pressure cook for 3 mins for al dente.