Preheat the grill. In a mixing bowl, combine the beef , horseradish, and garlic. Mix thoroughly. Season the beef with salt and pepper. Divide the mixture into four balls and form into firm round 3/4-inch patties. Place the patties on a hot grill. Cook the burgers for 4 to 5 minutes on each side for medium. During the last couple of minutes of cooking, place a slice of cheese on each patty. After the cheese has melted remove the burgers from the grill. Spread each half of the rolls with the butter. Place the rolls on the grill and cook for about 30 seconds to lightly toast the bread. Place the burger in-between each bun. Garnish each burger according to taste.