Scrub potatoes, dry and prick with a fork. Bake in a 425 degree oven 55 to 65 minutes, until soft. Reduce heat to 350. When potatoes are done, cut a slice from top of each. Carefully scoop out potatoes without breaking skins. Set skins aside.
Place potatoes in medium mixing bowl. Beat in egg, milk and butter; beat until smooth. Stir in remaining ingredients. Spoon potato mixture into reserved potato skins. Bake in a 350 degree oven 25 to 30 minutes or until heated through.