3. Line your cookie sheet with parchment paper and spread apple slices on to pan. You can fit about two sliced apples per pan. Shake cinnamon over them.
4. Bake at 275 for about 2 hours 15 minutes. Flip them over after an hour so they bake evenly and then check them every half an hour thereafter until they look crispy. If you want to make a large batch, just do one pan at a time. They get too hot too close to the bottom.