Cook potatoes in skins; cool. Peel and shred on a coarse grater. Combine cheese and 3 tablespoons margarine in saucepan; heat and stir until cheese is almost melted. Remove from heat; blend in sour cream, onion, salt, and pepper. Fold in potatoes, and spoon into a greased 2-quart casserole dish. Dot with 1 tablespoons margarine. Cover and bake at 300 degrees about 25 minutes. SOURCE: Southern Living Magazine, sometime in 1974. Typed for you by Nancy Coleman.