Wash and peel the potatoes then cut them into 2 inch pieces.
Place the potatoes in the pot of your Instant Pot and fill with enough water to cover the potatoes, approximately 4-5 cups. Add 1 tablespoon of kosher salt to the water.
Lock the lid in place and turn the valve to SEALING.
Set to HIGH PRESSURE for 10 minutes.
When the timer goes off press CANCEL and then let it do a natural release for 5 minutes.
Carefully turn the valve to VENTING and release the remaining steam.
Remove the lid and carefully remove the potatoes (be careful it will be hot!) and drain the excess water by pouring the potatoes into a strainer.
Put the potatoes back in the pot and add the butter and cream cheese. Use a potato masher or a hand mixer to begin mashing the potatoes. If your potatoes are a little dry you can add a small amount of milk until you reach the right consistency.