Peel, core and slice the apples into 1mm thick slices (mandolin is preferable to slice apples otherwise a very sharp knife is required).
Prepare a baking tray by lining with two layers of parchment paper. Sprinkle with icing sugar then lay the apple slices and sprinkle with some cinnamon and more icing sugar.
Lay more parchment paper over and bake in the oven for 50 – 60 minutes, turning half way through.
Set aside to cool. Store in an airtight container until required.