Peel the potatoes, rinse, and pat dry. Cut them into chunks and add to a pot. Add water to the pot (cover the potatoes with 1" of water over the potatoes).

Add a generous amount of salt to the water. Bring the potatoes to a boil over medium-high heat and cook until fork tender, about 13-15 minutes.

While the potatoes are cooking, add the butter pieces to a large mixing bowl (putting it at the bottom allows for the hot potatoes to melt the butter faster).

Drain the potatoes when they're done cooking and add them to the mixing bowl. Allow to sit for a couple of minutes so the butter can melt. Sprinkle with a generous amount of salt and pepper and add a couple of tablespoons of milk (start with only a few; you can always add more if needed).

Using a hand mixer, mix on medium speed until all the potatoes are blended and the mixture is smooth, adding more milk if necessary.

Stir in the sour cream until blended.

Optional step: transfer the potatoes to a baking dish and broil on high until the top has a few golden brown spots (watch it closely)! This step gives the potatoes an additional flavor.