Peel and cut the potatoes into uniform chunks. Place them in a pot and cover with cold water. Add 2 1/2 teaspoons of salt to the water.

Bring the potatoes to a boil over high heat. Reduce the heat to medium-low, cover, and simmer until fork-tender, 20 to 25 minutes.

Drain the potatoes and return them to the pot. Place them over low heat for 1 or 2 minutes to dry thoroughly.

Mash the potatoes, then add the butter and milk (or cream). Continue mashing.

Taste the potatoes and add salt and pepper as needed. Mix to combine and serve hot.