Preheat the oven to 200F (93C). Lay the parchment paper on one large or two medium baking sheets.
Using a mandolin or knife, thinly slice the apple to make round chips. Discard the seeds.
Lay the fruit slices on the prepared baking sheets without overlapping. Sprinkle the cinnamon over apples.
Bake for 1 hour, then flip the fruit slices. Continue baking for 1-2 hours, occasionally flipping, until the fruit slices are no longer moist. Let cool completely and then store in airtight container.
One serving could be served with peanut butter to increase the amount of protein.