Heat oven to 200C/180C fan/gas 6. Rub the butter into the flour and icing sugar with your fingertips, or blend in a food processor, until the mixture comes together in a ball – you don’t need to add any liquid or chill it. Knead briefly, then cut into 12 equal pieces.
Taking a piece of dough at a time, cut off two-thirds and press into the base and up the sides of a muffin tin hole. Repeat to make 12. Spoon the mincemeat into the pastry cases – it won’t completely fill them.
Now take the 12 remaining smaller pieces of pastry. Roll each into a ball and flatten to make a disc for the mince pie lid. Add one to each pie and tuck the pastry that comes up the sides of the tin down to seal it. Prick the tops with a fork a few times. Will freeze for up to 6 weeks. Defrost before baking.
Bake for 12-15 mins or until pale golden. Cool in the tins for about 10 mins, then give the pies a little twist to stop them from sticking. When cool, carefully remove from the tins. Dust with icing sugar when ready to serve.