Bring the butter and milk to room temperature.

Wash and dry the potatoes.

Peel the potatoes and slice them into 1/4" chunks.

Place the potato chunks in a large microwave-safe bowl. 

Cover the bowl with plastic wrap tightly. Poke a few holes in it.

Cook on high in the microwave for 7 minutes.

Using potholders carefully remove the bowl from the microwave and carefully remove the plastic wrap. Be careful because there will be steam.

The potatoes should be fork-tender. If they are not, cover the bowl and cook the potatoes for another 2 minutes and check them again. When the potatoes are fork-tender, move on to the next step.

Using a hand mixer, mash the potatoes until they are smooth.

Add in the butter, and milk.

Stir to fully combine. 

Add salt and pepper to taste as desired.

Serve hot.