Peel the potatoes and place them in a large stockpot. Fill water to 1-inch above the potatoes. Bring the water to a boil, then turn the heat to a simmer. Cover the pot, and cook for 15-20 minutes. Check for doneness by piercing a potato with a fork. Drain.
Let potatoes cool. Process through potato ricer or use a potato masher.
Stir in the butter and season with salt. Taste and adjust with additional salt and/or butter if needed. If the mashed potatoes isn't quite creamy enough, add more butter.