First make the pastry - Place the flour, confectioners' sugar and butter in a food processor and pulse until fine crumbs form. Add the orange zest and egg and pulse again until it just comes together (add a couple of drops of cold water if it's still too crumbly to come together).
Place the pastry on a piece of lightly floured baking parchment. Squash together to form it into a ball, then roll it out to ¼ inch thick with a lightly floured rolling pin.
Place in the fridge to chill for 30-60 minutes (cover with clingfilm if leaving in the fridge for longer - up to two days).
Whilst the pastry is chilling, make the frangipane. Place the butter and sugar in a large bowl and beat it together with a wooden spoon or hand mixer for a couple of minutes – until it goes paler. Stir in the egg and almond extract until mixed, then stir in the ground almonds. Place in the fridge until you’re ready to use it.
Preheat the oven to 190C/375F
Once the pastry is chilled, cut out rounds using an 8cm/3" fluted cutter. Re-roll the pastry as necessary. You should get 18-20 rounds. Press each piece of pastry carefully into the hole of a 12-hole cake tin (a regular fairy-cake tin - not a muffin tin). You'll need two trays.
Fill each pastry- hole with a tablespoon of mincemeat, then top with a tablespoon of frangipane and smooth the top slightly (it will spread as it cooks, so you don't need to be too neat). Be sure not to top with too much frangipane, as it will overflow. Sprinkle with the flaked almonds and place in the oven for 15-20 minutes until golden brown.
Take out of the oven and leave to cool before sifting over a little confectioners' sugar, then serve.