1. Wash the apples
2. Core the apples (not mandatory, but it'll make slicing them a lot easier)
3. Pre-heat the oven to 225'F or 105'C. Don't change the temperature as we want them to dehydrate, not turn them to charcoal.
4. Slice the apples very thin. About 1 mm is just right. (That is about 0.04 inches for all you folk with the weird ancient metric system) If you have a potato slicer or thin slicer, those will generally have a good size by default.
If your thin slicer isn't quite the same width as your apple then you can slice the apple by twisting it on the blade like you were twisting a screw, this way you'll get a nice long single slice which you can then break up into the desired shapes. (See image below)
5. Apply the cinnamon and sugar. This can be done in two ways depending on your preference.
5.1. Pre mix the powdered sugar and cinnamon into a bowl, the put each apple slice in the mixture before putting it ready for the oven.
5.2. Lay out all the apple slices (as I did in the image below), then richly apply the cinnamon and sugar on one side.
6. Insert the apple slices into the oven and leave for 1 hour.
7. After 1 hour, turn the slices around and set the clock for another hour. You'll notice they're probably still a little soft. The next hour will fix that.
8. Remove the slices from the oven and leave to cool for a few minutes.
9. Dig in!