Preheat the oven to 250° F. Place the potatoes in a large pot and fill with enough water to cover. Add the salt and bring to a boil over high heat. Reduce the heat to medium and simmer until the potatoes are tender- (about 12 to 15 minutes). Drain the potatoes, transfer to a rimmed baking sheet, and place in the oven until thoroughly dried out – 7 to 8 minutes.
MASH THE POTATOES:
Mash the potatoes until smooth, taking care not to overwork them. I like to use a potato ricer. Add the butter and milk a little at a time, mashing them into the potatoes. Stir in the pepper. Add additional salt, if desired.