With a sharp knife, make a cut on each chestnut, slicing the rounded side horizontally (just like I show in the video). This step is essential to stop the chestnuts from exploding while cooking — and yes, that can actually happen. Chestnuts are quite hard, so take your time and watch your fingers.
Cook in the air fryer at 200°C (390°F) for 15 minutes.
As soon as they’re done, transfer the chestnuts straight onto a clean tea towel and wrap them up. This keeps them warm and steamy, making them much easier to peel. Peel one by one, keeping the rest wrapped while you work.