Preheat the oven to 180°C/gas mark 4. Use a sharp knife to carefully slice the apples into very thin rounds – cut right through the core and the seeds will fall out.
CHILDREN: Line 2 baking sheets with baking parchment and arrange the apple slices in a single layer. Sprinkle with the cinnamon and bake for 20 minutes.
Turn the oven up to 200°C/gas mark 6 and bake for a further 10 minutes until chewy.