Using a spoon, make shallow trough in cut side of potato to hold filling, leaving at least a ¼" border around edges. Be careful not to take too much potato out, just enough to keep filling from sliding off. Brush potatoes with butter, season lightly with salt and pepper. Turn potatoes over and butter and season the skin side. Place them on a baking sheet skin side up and broil 2–3 minutes until starting to brown. Turn skins over and broil 2–3 minutes more then remove from oven.