Preheat the oven to 200˚F. Spray the baking sheets with coconut oil. Rinse and core the apples. Using a mandolin, slice the apples to about ¼ in. Lay the slices flat on the baking sheets. Place the sheets in the oven for about two hours or until the apples are completely dry. In a sealed container these chips can be stored at room temperature for two days.