Preheat oven to 200°F. Line two large baking sheets with parchment paper.
Wash the apples. With an apple corer, knife, or the round side of a metal piping tip, core the apples (you can skip this step if you don't care about the seeds).
Using a mandoline, set to ⅛ inch thick and slice the apples horizontally. You can also use a knife but obviously it's hard to remain consistent.
Arrange the apples in a single layer on the two baking sheets. Sprinkle the apple pie spice over the apples. Bake for 1 ½ hours then flip the apples and bake for another hour.
You'll know they're almost done when you remove one apple chip and it's crispy after 2-3 minutes. Turn oven off and let the apples sit for 1 hour. Remove and serve immediately or store in airtight container at room temperature for 1 week.
Notes
Pick good, fresh apples.
Slice the apples thin and consistent. Using a mandoline helps but you can use a knife if needed. You want them to be ⅛ inch thick.
Mix it up with the spices. I personally love to use apple pie spice but you can use cinnamon with sugar, ginger, nutmeg, cloves or even pumpkin pie spice. Yes pumpkin pie spice will work just fine as it is just a combination of the spices mentioned previously.
Lay the apples in a single layer so they cook evenly.
Cook the apples low and slow. Bake at 200°F for 2-3 hours. Mine take about 2.5 hours.
Let the apples sit in oven for an hour with the oven turned off. The apples become crispy as they cool.