Line the base of your air fryer with foil. Cut the pastry sheet in half lengthways, then cut each half into three pieces, so you have six in total. Score an edge of about 2cm around each piece, being careful not to cut all the way through. Put in the fridge to chill while you prepare the apple.

Core and quarter the apple, then cut each quarter into thin slices. Put the apple in a bowl, add the lemon juice and toss. Add the cinnamon and caster sugar, then mix well to coat.

Put the apple slices into the centre of the pastry, being careful not to go over the border you scored earlier. Chill in the fridge for 20 mins.

Heat the air fryer to 180C. Cook the tarts for 25-30 mins until the pastry is cooked and the apple has started to turn light golden.