Sift the flour and icing sugar together into a bowl and stir in the ground almonds. Add the butter and rub into the flour until the mixture resembles fine breadcrumbs
Stir in the the orange zest, make a well in the centre and drop in the egg yolk and 2 tbsp of water. Mix together to form a dough adding a little more water if required. Cover and rest the pastry for 20 minutes in a cool place.
Preheat the oven to gas 200C/400F/gas mark 6. Roll out about two-thirds of the pastry on a lightly floured work surface and using a 7½cm (3in) round cutter, cut out circles and use to line bun trays to form pastry cases.
Stir the orange juice into the mincemeat and spoon a little into each pastry case.
Roll out the remaining pastry and cut out lids using a small round or star cutter. Place lids on top of the mincemeat.
Beat the egg white with a fork until broken up and slightly frothy. Brush onto the pastry lids and sprinkle with a little caster sugar.
Bake in the centre of the oven for 12 to 15 minutes or until golden. Transfer to a wire rack to cool.
Nutrition information is calculated using an online nutrition database - is approximate and is meant as a guideline only.