Preheat broiler. Place bread, cut sides up, on a foil-lined baking sheet. Spread with butter.
Broil 3 to 4 inches from the heat for 1 to 2 minutes or until browned. Sprinkle with cheese. Broil for 1 to 2 minutes more or until cheese is melted and lightly browned. Cut bread into slices and serve warm.