Add olive oil to the inner pot of an Instant Pot. Turn on to "Saute" mode. Add onion and ground beef. Cook until no longer pink. Drain off any excess grease. Turn Instant Pot off.
Add Italian seasoning, salt, pepper, garlic powder, crushed red pepper flakes and tomato paste to the beef mixture. Stir together.
Add shell pasta on top of ground beef mixture. Pour pasta sauce and water on top of shells. Do not stir, but press shells down into liquid with the back of a spoon.
Place lid on Instant Pot. Be sure valve set to "sealing". Set to cook on HIGH for 5 minutes.
Do a manual pressure release. Stir in Parmesan cheese, heavy cream, and cream cheese. Serves 6.