Preheat oven to 240F
Core each apple, using the corer
Slice each apple about 1/4" thick using the mandoline slicer
Mix cinnamon and sugar together and toss with the apples to coat.
Place apple slices on a metal baking sheet and bake for 2 hours, or until the edges are curled and dry.
Transfer slices to a wire rack to allow to cool and completely dry.
Store any leftovers in an airtight container for up to 4 days