Turn the Instant Pot to saute. When it reads "hot" add the oil.
Add the chicken breasts, sprinkle with salt and pepper, and brown on both sides, about 3-4 minutes total.
Add the garlic, parsley and oregano and stir and cook 1 minute.
Add the chicken broth, and scrape the bottom of the pot with a hard metal spoon to remove any stuck on bits. Turn the Instant Pot off.
Add the pasta -- don't stir -- and press down with a spatula into the liquid. The liquid will just barely cover the pasta.
Put the lid on, turn the valve to sealing, and select Manual or Pressure Cook for 3 minutes.
When the cook time is over, do a quick release (open the valve all the way) and remove the lid. Turn the Instant Pot to saute.
Stir in the cream cheese, mozzarella, and Parmesan. Stir together the water and corn starch and stir into the pasta. Cook and stir until thickened and season to your tastes. Serve.