Rub the butter into the flour and icing sugar until it resembles fine breadcrumbs. Bring together with the beaten egg and orange zest. Wrap and chill for at least 30 minutes.
Stir the brandy or rum through the mincemeat if using.
Roll out the pastry to 3mm thick, cut circles and press into a muffin tin. Fill each with a heaped teaspoon of mincemeat.
Cut star lids from the remaining pastry, place on top, brush with beaten egg, and bake at 200°C (180°C fan) for 15-20 minutes until golden. Cool then dust with icing sugar.