Preheat oven to 350°. Place a lightly greased wire rack in an aluminum foil-lined 15- x 10-inch jelly-roll pan. Cut apple into 1/16-inch-thick slices, cutting through stem and bottom end using a mandoline. Bring sugar and water to a boil in a 3-qt. saucepan over medium-high heat, stirring constantly. Add apple slices, and cook, stirring often, 10 to 12 minutes or until apples are slightly translucent and syrup begins to thicken. Remove from heat. Quickly remove apples from syrup, 1 at a time, using tongs, and place in a single layer on wire rack in pan. Discard remaining syrup, or save for another use. Bake apples at 350° for 10 to 15 minutes or until golden; remove from oven, and transfer apples to lightly greased wax paper, using tongs. Cool completely (about 10 minutes). Apples will crisp as they cool.