Halve large grapefruit. Remove seeds and core. Run sharp knife between pulp and skin, and loosen sections of pulp. Place in baking pan, sprinkle each half with 3 tablespoons brown or white sugar and dot with butter. Broil about 5 inches from broiler heat, 10 to 15 minutes. Note: 1 tablespoon sugar may be replaced by 2 tablespoons grape juice, or honey may replace all of the sugar. Sherry may be sprinkled over the fruit just before serving.