Slice apples in uniformly thin slices (1/8 of an inch or less) and place on a parchment or silicone baking mat lined baking sheet in an even layer. Slices can touch each other, but try not to overlap. Fit as many apples on a sheet as you can (they shrink a lot!).
Mix sugar and cinnamon together in a small bowl. If desired, sprinkle with the cinnamon sugar and gently rub in.
Bake apples at 170 degrees for 6-8 hours, until dry and slightly shriveled and curled up around the edges.
Turn off oven and leave door shut until completely cooled. Remove apples from baking sheet and store in an airtight container.
*Alternately, instead of cinnamon, you can sprinkle with dry fruit flavored gelatin (ignore instructions on box and just sprinkle with the dry powder sugar or sugar free). This will make bright colored apple chips your kids will love.