Preheat oven to 225ºF.
Line 2 large baking sheets with parchment paper.
In this step, you can choose to either core your apples or just slice them and remove the seeds. I personally like to core my apples and leave the skins on but you can peel them if you like.
Using a sharp knife or a mandolin (if you have one) slice the apples as thinly as possible about 1/8" thick.
Place apple slices on prepared baking sheets. Sprinkle with cinnamon & sugar if desired.
Bake the slices for 1 hour. After 1 hour, remove from oven and turn/flip each slice over; return the pans to the oven. Bake 1 more hour for soft dried apples or about 2 more hours for crispier apple chips. (Timing depends on your oven and how thick the apples were sliced. Check occasionally and reduce or increase total time as needed.)
Store in an airtight container for up to 1 week or refrigerate for up to 1 month.
