Clean, peel, and slice your potatoes. Slicing the potatoes into large rounds is my favorite method.
Add the potatoes, water, and salt to the instant pot. Secure the lid.
Turn the pot to high pressure/manual and set the timer for 10 minutes. It will take the instant pot about 7-10 minutes to come to pressure before that 10 minutes starts counting down, hence the 20-minute total cook time.
Once the 10 minutes is up and the pot beeps, do a manual release.
Add the butter and milk to the potatoes, then blend them right in the instant pot until they are smooth and creamy. Enjoy!