Bring potatoes and cold water to cover to a boil in a large Dutch oven; boil 35 to 40 minutes or until tender. Drain and cool. Peel potatoes, and mash with a potato masher or fork until smooth.
Stir in sour cream and next 4 ingredients; fold in cheese. Spoon into a lightly greased 2-quart baking dish. Top evenly with 2 tablespoons cold butter, and sprinkle evenly with paprika.
Bake, uncovered, at 350° for 30 minutes. Garnish, if desired.