Whizz together the flour, icing sugar and butter until they form fine crumbs. With the blades running, add the zest, then the egg and process for a few secs until the mixture forms clumps. If you need to, work in a few trickles of ice cold water, but try and avoid it if you can for the shortest pastry.
Tip onto a very lightly floured surface, knead briefly until smooth, then chill in the fridge for 30 mins or until firm. Can be made up to 3 days ahead or frozen for up to a month.
Lightly dust the work surface with flour, then roll pastry out to approx 1 thickness.
Cut out 12 x 8cm rounds with a fluted cutter and press into a 12-hole non-stick bun tin. Re-roll the trimmings to the same thickness and stamp out 12 x 5cm rounds for the tops. If you like, use a star cutter to cut out star shapes in the top of the pies, or simply cut crosses in the middle.
Spoon about 1 dessertspoon mincemeat into each base, sprinkle with cranberries, then press on the tops. Chill for 20 mins while you heat oven to 190C/fan 170C/gas
Can be frozen for up to 1 month at this point.
Brush the tops with the egg, then bake for 15-20 mins until golden and crisp. Cool for a few mins, then lever out of the tins with a table knife and cool on a wire rack. Store in an airtight container for up to 1 week. Warm gently to serve, dusted with sifted icing sugar.
