Hit SAUTE on the Instant Pot, and when it reads Hot, add the olive oil and sausage
Add the Italian seasoning and garlic powder, and cook sausage until brown and no longer pink, stirring frequently and breaking up sausage with a spatula or wooden spoon
Hit CANCEL, and deglaze pot with some of the water (about 1/2 cup) to loosen up browned bits from bottom of pot, if necessary
Add the uncooked pasta over the sausage, and add remaining water over and around pasta. Top with marinara sauce, and spread over pasta, but Do Not Stir!
Cover pot with lid, and turn vent to Sealing position. Hit PRESSURE COOK for 5 minutes. Pot will take a few minutes to reach pressure, then begin counting down and cook for 5 minutes
When pot beeps, turn vent and do a quick release or gradual quick release, to control liquid spraying out of pot
When pin drops, carefully remove lid, and stir pasta. Stir in the cream, and gradually stir in the Parmesan cheese
Serve pasta topped with shredded mozzarella cheese, if desired