heavy cream, room temperature
Peel the potatoes and cut into 1-inch wedges. Add enough cold water to cover the potatoes. Add 1 teaspoon salt. Bring to a boil over high heat.
Reduce heat to medium low and simmer until potatoes are fork tender. This takes about 25 minutes.
Drain potatoes in a colander. Return to saucepan. Heat over medium low heat 2 - 3 minutes to dry potatoes. Stir occasionally.
Add the butter, cream, more salt, and black pepper. With the heat on medium low, mash and stir the mixture until well blended. About 4 - 5 minutes.
To keep mashed potatoes hot, heat the cream before adding to the potatoes. When prepared ahead of time, keep mashed potatoes warm by placing in top of double boiler or over a pot of hot water.