Set out a scale and the equipment for Mashed potatoes. Heat to a quiet simmer, about 195°F / 90°C and give it 5 minutes so the surface is actually hot. Weigh potato, unsalted butter, whole milk, black pepper, kosher salt. Mashed potatoes is cooked in Thanksgiving as its own plate, not as a copy of a restaurant menu. Boil the potatoes until a knife slips in, then mash them with warm milk and butter until they are smooth and still a little rough. Amounts are for 4 from foods this library can count.