Core and slice an apple. (Gala if you have it). Spread one tablespoon of peanut butter onto one side of 8 slices of bread.
Arrange apple slices on 4 slices of bread. Sprinkle the cinnamon evenly over the apples. Top with the remaining 4 slices of bread, peanut butter face down.
Spray a large skillet with cooking spray and pre-heat to medium heat. Cook sandwiches until browned, about 1 to 2 minutes on each side.