Mix the flour, cocoa, butter, sugar and mixed spice in a food processor and process until the mixture resembles fine breadcrumbs (or you can use your fingers).
Add the egg and vanilla then mix it until you get a dough. Flatten it into a disc, then refrigerate for at least 30 minutes, wrapped in clingfilm.
Preheat oven to 170°C .
Roll out the dough to a thickness of 3mm. Using a 7-8 cm round cutter or cup, stamp out 12 disks. Put these into the holes of bun or scone tin.
Add a spoonful of mincemeat to all cases.
Re-roll the remaining dough, then using a smaller (about a 6cm round cutter), cut out 6 circles. Using star-shaped cutters, cut out stars from the circles.
Put the stars on top of 6 pies, the other cut-out disks on top of the remaining cases. Press the edges together with your fingertips.
Bake for about 20 minutes or until the pies are golden.
Let them cool for 5 minutes, then dust with icing sugar and serve.