Cream butter and the cup of sugar; add well-beaten eggs, then milk, vanilla, flour, salt, and baking powder. Refrigerate for at least 1 hour. Roll dough, cut into trefoil shapes, and sprinkle sugar on top, if desired. Bake in a quick oven (375°) for approximately 8 to 10 minutes or until the edges begin to brown. Makes six- to seven-dozen cookies.