Peel and cut potatoes and cook in 5 quart pan until tender. Drain and mash well. With electric mixer beat together cream cheese and sour cream. Gradually beat together and add to mashed potatoes until smooth. Beat in garlic salt and pepper. Turn mixture into a buttered shallow 3 to 4 quart casserole (13x9 inch). Dot with butter. Sprinkle paprika on lightly. Cover and chill. Good up to 3 days in refrigerator.
Reheat: Bring to room temperature. Cover and bake 400 degree oven for 50 to 60 minutes, or till hot throughout.