How thinly do you slice the apples?

This particular recipe specifies "thinly sliced," and in that case I usually shoot for close to an 1/8th of an inch. If this feels a little tricky, aim for a 1/4—just do your best to make them uniform, that way they'll all cook evenly.

I like to slice them about 1/4" so they retain some crunch, but there are so many other variables such as oven temp and apple variety.