Peel and boil potatoes till soft. Mash well. Mix in remaining ingredients, beating until light and fluffy. Spoon into buttered 2-qt casserole dish. Top with one of the following: 1/2 cup brown sugar mixed with 1/4 cup pineapple, coconut or nuts. Add marshmallows the last 5 mins of baking. Bake at 350 degress for 20 minutes.