Add the olive oil, ground beef, onions and garlic into the Instant Pot and set it on sauté mode. Season mixture with Italian seasoning.
Brown and crumble the beef until it is no longer pink and the onion has softened. Drain any excess grease. Make sure you don't have any brown bits left in the bottom of the pot - you don't want them to burn later as the pot is coming to pressure. Place drained beef back into the pot.
Turn the Instant Pot off the sauté mode.
Add the marinara in with the beef mixture and stir to combine.
Add the uncooked ziti noodles onto the top of the sauce mixture, but DO NOT STIR IN.
Pour the 2 cups of water over top of the uncooked pasta. Again, DO NOT stir.
Place the top on the Instant Pot, seal and set manual setting on HIGH pressure for 7 minutes.
When the timer goes off, to a quick release of the pressure immediately and turn the IP off
Open the top and add 1 cup of cottage cheese and stir into the pasta and tomato sauce mixture.
Cover the top of the ziti with mozzarella cheese as a topping. DO NOT stir again.
Place the lid back on and let it sit for at least 5 minutes to let the cheese melt.
Store leftovers in an airtight container in the refrigerator for up to 4 days.
Substitute ricotta cheese for the cottage cheese, if desired.
Ground Italian sausage can be substituted for the ground beef.
Add ¼ cup of parmesan cheese in with the cottage cheese, if desired.
Add more mozzarella cheese if you prefer an even cheesier version.