Heat griddle or large skillet over medium-low heat. Spread Dijon on 4 slices of bread. Top with slices cheese, 3 pieces of bacon and apple slices. Place the remaining bread on top and spread top piece of bread with butter. Place on skillet buttered-side down and butter the remaining side. Cook until cheese is slightly melted and bread is golden brown. Flip the sandwich and continue to cook until cheese is thoroughly melted and bread is golden brown. Makes 4 sandwiches.