Place the potatoes in a pan and cover with cold water. Add salt and bring quickly to a boil. Lower the heat and cook until the point of a sharp knife is easily inserted. Drain. Rub the potatoes through the fine mesh of a food mill. Replace in the pan and over a low heat beat in the butter and the boiling milk. Taste for seasoning and add a little pepper and some nutmeg (if you like). When new potatoes are in season, cook them in their skins. Potatoes must be just cooked to produce a delicate purÄe.
