Heat oven to 225F and line two baking sheets with parchment.

Slice the apples as thinly as possible, ideally with a mandoline.

Arrange the slices in a single layer and sprinkle with the cinnamon, sugar, and salt.

Bake 1 hour, flip the slices, and bake 1 more hour until dry.

Turn off the oven and let the chips crisp inside for 15 minutes.

Cool completely so they crisp up fully.