Peel and chop the potatoes into 2-inch thick chunks. Rinse under cold water.

Place the potatoes in a large pot and cover with cold, salted water. Bring to a boil, then simmer for 15-20 minutes until fork-tender.

Drain the potatoes and return to the pot. Allow to steam for a minute over low heat.

Using a potato masher, mash the potatoes until smooth.

Melt the butter and pour it along with hot milk or cream into the mashed potatoes. Stir until creamy.

Season with salt and pepper to taste, mixing thoroughly.