Preheat oven to 100°C. Line 2 large baking sheets with parchment paper.
Whisk 3 tablespoons icing sugar with 3 tablespoons maple syrup and set aside. Sift remaining 3 tablespoons icing sugar evenly onto lined baking sheets.
With a mandolin or other manual slicer cut apples crosswise into paper-thin slices. Arrange apple slices in one layer on sheets and brush with maple syrup mixture.
Bake slices for about 2 hours (rotating pans halfway through cooking), or until slices are pale golden and starting to crisp. Brush apple slices with remaining 3 tablespoons syrup and sprinkle with chopped pecans and cinnamon.
Bake an additional 20 minutes. Immediately peel apple bites off parchment and cool on a rack.