In the bottom of the Instant Pot, place pasta only (not the cheese packet contents), 3 cups of water and 4 Tablespoons of butter cut into small cubes. Give a good stir and seal the lid on the Instant Pot.
Set the Instant Pot to Manual (on high) for 3 minutes.
While the Instant Pot is coming to pressure and cooking for 3 minutes, mix together 1/2 cup milk and contents of the two powdered cheese packets. Stir until it forms a thick, creamy sauce.
Once the 3 minutes is up, carefully release the pressure. Not NPR (natural pressure release), you'll want to use your left hand with an oven mitt on it and carefully turn the release valve toward you.
Once the pressure has released and the pin has dropped, remove the lid. Stir in the cheese sauce and eat right away.