Rinse and dry the apple. Slice across the apple making 1/2-inch slices. Alternatively, a mandolin may be used.
Spread 1 teaspoon of peanut butter on each apple slice making up an apple peanut butter sandwich. If filling is desired, sprinkle that on top of the peanut butter on one apple slice and place the second apple slice, peanut butter side down on top of the filling.