Preheat the oven to 200°C / gas mark 6. Mix together the shop bought mincemeat with the cranberries and lemon zest.
Roll out the pastry until it is 2mm thick. Stamp out 12 x 6cm rounds with a pastry cutter and lay on a baking tray lined with greaseproof paper.
Fill each case with one heaped teaspoon of mincemeat and brush the edges with a little egg wash.
Stamp out 12 x 6cm fluted rounds for the lids and put on top of the mincemeat, sealing to the edges of the bases, by pressing down gently with the tips of your fingers. Brush with the egg yolks and sprinkle lightly with golden caster sugar. Make a little hole on top. At this point you can transfer to a freezer-safe container to cook from frozen later. Please note, cooking times will increase when cooking from frozen and you may need to lower your oven temperature slightly.
Bake in the oven for 20 minutes until golden brown sprinkle with the sugar and cool or serve warm.