Preheat oven to 350 degrees. Lightly grease a wire rack with cooking spray and place in a 15x10-inch jelly roll pan.
Bring sugar and water to boil in a medium saucepan and stir frequently.
Using a mandoline, slice apples into 1/16-inch thick slices.
Quickly, before they start to brown, place apples in boiling sugar mixture. Turn heat down to a simmer. Cook apples, stirring often, until translucent and syrup starts to thicken, about 10 to 12 minutes.
Remove from heat and quickly remove apples from syrup 1 at a time using tongs and place flat on wire rack set inside jelly roll pan. Discard excess syrup.
Bake apples 10 to 15 minutes, or until golden. Transfer to lightly greased wax paper. They will feel soft at this point but will crisp up as they cool.