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.