How to Make It
In a large saucepan, cover the potatoes with water and bring to a boil. Add 2 tablespoons of salt and simmer until tender, 15 to 20 minutes. Drain well and let stand in a colander for 3 minutes.
Pass the potatoes through a ricer into the large saucepan. Cook over moderate heat, stirring with a wooden spoon, until the potatoes are hot and steam starts to rise, about 2 minutes; they’ll start to stick to the bottom of the pan. Add one-fourth of the butter cubes at a time, stirring constantly until incorporated. Stir in the heavy cream and season generously with salt. Serve right away.