Place 3 slices cheese on each of 4 slices bread. Top with remaining bread slices. Spread 2 teaspoons butter over each top slice of bread.
Place sandwiches, butter sides down, in skillet. Spread remaining butter over top slices of bread. Cook uncovered over medium heat about 5 minutes or until bottoms are golden brown. Turn and cook 2 to 3 minutes longer or until bottoms are golden brown and cheese is melted.