Preheat oven to 200ºF. Using a mandoline slicer, thinly slice the apples to 1/8” thickness.
Line two large sheet pans with parchment paper or silicone mats. Lay apples slices on top of parchment (or mats), spacing them so that no apples overlap.
Sprinkle cinnamon evenly over the apple slices.
Bake apple slices for about 2 hours, flipping halfway through, until they are pliable yet dry to the touch. The apple slices will crisp as they cool.
Because finished apple chips will to absorb moisture from the air, they are best enjoyed shortly after baking. For storage, seal leftover apple chips in an airtight bag or container and remove as much air as possible to prevent softening.