Roll out the pastry on a lightly floured surface until roughly ½cm thick. Use an 8-10cm round biscuit cutter to stamp out as many discs as you can, then reroll the offcuts and cut out more, using up as much of the pastry as possible. Spoon 1 tbsp mincemeat into the middles of half the pastry discs. Stamp out small stars (or other festive shapes) from the middles of half of the remaining pastry discs and set aside. Beat the egg and brush lightly around the edge of each mincemeat-topped pastry disc. Place the lids on top – some with the stamped-out stars and some without. Brush a little egg wash over each pie, then stick the leftover stars on top of the plain pastry pies. Brush the stars with egg wash, too. Poke a little hole in the top of the covered pies to let steam escape during cooking. Either use a fork to seal the edges of the pies by pressing around the edge, or make a small, neat crimp by pinching with your fingers. Arrange the pies on a plate or baking tray and chill for at least 30 mins. Will keep frozen for up to two months. Heat the air-fryer to 180C. Lay a square of baking parchment in the air-fryer basket, sit the pies on top, cooking as many as you’d like at a time. Cook for 8-10 mins, then turn the mince pies and cook for a further 2-3 mins, or 13-15 mins from frozen. The pies should be golden brown and steaming hot. Leave to cool for 5 mins, then dust with icing sugar and serve. Will keep in an airtight tin for up to two days.