Put the butter, flour, salt, almonds, half the zest, cinnamon and sugar into a food processor and blitz until you have a mixture that resembles breadcrumbs.
Take out 200g of the mix and put it into a bowl. Continue to mix the rest in the food processor, adding ½ tbs of very cold water, until the pastry has come together in a ball.
Flatten into a disc, wrap in cling film and put in the fridge for an hour.
Lightly butter the holes in two 12-hole tart tins then dust them with flour and tip out the excess.
Mix the mincemeat with the dried cranberries, port and the rest of the orange zest.
Roll the pastry out on a lightly floured surface until it is 3mm thick. Cut out circles to fit the holes in your tin, then press them into the holes.
Using a teaspoon, fill the tart cases with the mincemeat mixture.
Sprinkle the reserved crumble mixture over the top of each tart and bake in an oven preheated to 190°C for 35 minutes.
Leave to ‘set’ in the tray for about 20 minutes, then carefully lever them out (using a knife to run round the edges, especially if the mincemeat has bubbled out).
Put onto a wire cooling rack and leave to cool completely.
Sift on the icing sugar before you store or serve them.