Peel and quarter the Yukon Gold potatoes.
Place the potatoes in the Instant Pot.
Add the chicken or vegetable broth to the pot.
Close the lid securely and set the valve to sealing.
Select the manual setting and cook on high pressure for 12 minutes.
Once cooking is complete, allow a natural release for 10 minutes.
Carefully switch the valve to venting to release any remaining pressure.
Open the lid and drain excess liquid if necessary.
Add the softened butter and milk or cream to the potatoes.
Mash with a potato masher or use a hand mixer until creamy.
Season with salt, pepper, and optional garlic powder to taste.
Garnish with chives if desired.