Mash with a potato masher or beat with an electric mixer on low speed until smooth.
With a pastry bag fitted with a star tip; pipe potato mixture into six or eight large star shapes onto baking sheet.
Freeze about 45 minutes or until firm. Remove potato mounds from baking sheet and transfer to a plastic zippered freezer bag, removing all air from bag as sealing close. Freeze.
To serve, place frozen potato mounds on a greased baking sheet. Brush with two tablespoons melted butter or margarine. Bake, uncovered in a 375-degree oven for 20 to 25 minutes or until heated through.