Preheat oven to 95 °C/200F degrees.
Using a sharp knife or mandolin, slice apples thinly and discard seeds.
Prepare a baking sheet with parchment paper and arrange apple slices on it without overlapping.
Sprinkle cinnamon over apples.
Bake for 1 hour, flip the apples over, and bake for another 1-1.5 hours.
Turn the oven off and keep the apples inside as the oven cools down for 1 hour.This will help them get crunchy. Some apples may just be chewy and only slightly crunchy after 3 hours in the oven.
Store apple chips at room temperature in an airtight container for up to 1 week.