Bake the potatoes fully done, wrap in a dishtowel and carefully roll or squeeze to tenderize the pulp without breaking the skins. Cut off a slice of potato skin from each hot potato. Put slices aside for crispy potato peels, carefully scoop out pulp, leaving a thin shell. In a bowl, mash pulp until smooth. Beat in sour cream, cheese, onion, milk, butter, parsley and salt. Fill shells; brush with butter and press on a layer of grated cheddar. Cover and refrigerate until cold. Wrap shells individually in plastic wrap; place in freezer containers. Freeze. To serve, thaw and place in an ungreased shallow baking dish. Bake, uncovered, at 400 degrees for 30 - 35 minutes or until golden and heated through