Preheat oven to 300. Line 2 baking sheets with parchment paper.
Slice apples thinly with a mandoline slicer (I used number 1 thickness). Hold the bottom of the apple to the slicer and slice away (the seeds will fall out as you do).
Lay apple slices on baking sheets, trying not to overlap the slices too much (but they will shrink a lot in the baking process). Sprinkle with cinnamon.
Bake for 1 hour at 300. Remove from heat and enjoy!