Set your Instant Pot to sauté. Add the olive oil and butter and allow it to sizzle. Add garlic cook for 1-2 minutes or until translucent. Stir regularly.
Add your chicken and cook until browned, about 3-4 minutes, or until no longer pink. Drain grease and set aside in a medium-size bowl.
Add water and then your dry pasta to your Instant Pot and stir together to be sure the pasta is submerged in the water
Set Instant Pot to high pressure for 10 minutes. Lock lid and make sure vent is closed. When cooking time ends, release pressure and wait for steam to completely stop before opening lid. Remove pasta and add to the bowl of chicken.
Press sauté function on Instant Pot. Add cream, mustard, flour, and thyme to pot. Stir continuously until mixture is thickened; about 2 minutes.
Add chicken and pasta back to the pot.
Stir in cheese and allow to melt. Serve immediately.