In a small bowl, mix together the spices and brown sugar.
Preheat oven to 230F. Line baking sheets with parchment paper.
Slice apples thinly (peel on) with mandolin slicer. Each apple should make at least 12 slices. Discard seeds. Lay slices flat on parchment paper, and sprinkle on the pumpkin pie spice mixture.
Bake for one hour. Then flip apple slices over. If you want a stronger flavor, you can sprinkle on more of the pumpkin pie spice mixture, but for presentation, it’s nice to leave one side white.
Bake for another hour or until slices begin to lightly brown (will take longer if you are baking more than two apples). Turn oven off, but do not take out the apple slices yet. Allow the apple slices to slowly cool, and crisp up in the oven, about 20-30 minutes.