Using a mandolin slicer, cut apple into 1/8-inch-thick slices. Depending on the size of apple, this should yield approximately 15-25 slices.
Arrange apple slices in rows on a parchment-lined cookie sheet. Make sure that apples do not overlap. Sprinkle evenly with cinnamon.
Bake at 225° for 3 hours, turning once, until slices dehydrate and edges curl. Remove chips and cool on a baking rack. Store in an airtight container for up to two days.