Add the macaroni, water, salt, and butter to the Instant Pot, then seal and set to cook (on manual/high pressure) for 4 minutes.

After the timer goes off, immediately release the pressure and remove the lid.

Add the cream cheese and milk to the pot and stir to combine. Once the cream cheese has melted, add the shredded cheese and pepper and stir again.

Taste for seasoning and add additional salt if needed. If the sauce is too thick, add another tablespoon of milk one tablespoon at a time until you reach the right consistency. Once the cheese is fully melted, serve immediately.