1. Put potatoes in a large saucepan, and cover with cold water. Add 2 tablespoons salt. Bring to a boil. Reduce heat to medium-low, and simmer until tender, about 10 minutes. Drain potatoes in a colander.

2. Heat milk in a small saucepan over medium-low heat. Press the potatoes through a ricer into a heatproof bowl set over a pan of simmering water; stir until smooth. Pour in warm milk in a slow, steady stream, stirring constantly. Stir in butter, and season with salt and pepper