Place potatoes in a small saucepan and cover with water. Bring to a boil. Reduce heat; cover and cook for 8-12 minutes or until tender.
Drain potatoes; mash with milk, sour cream, butter, salt and pepper. Transfer to a greased 2-cup baking dish. Sprinkle with cheese. Bake, uncovered, at 350° for 10-15 minutes or until heated through and cheese is melted.