Bake potatoes in a 350-degree oven for about 45 minutes or until the potatoes are done, test doneness by piercing them with a fork. Slice the ends of one side of each of the potatoes. Line the potatoes together by lining up the cut ends.
Split the potatoes open side. Roughly chop the roast beef, and place on potato. Cover with cheese, and place back into the oven until the cheese is melted. Remove potato from oven, and place on a serving dish. While the cheese is melting heat up the beef gravy. Serve potato with beef gravy poured on top. Optional ingredients may be sour cream, chopped red onion, or chopped green onion.