Sift the flour into a bowl with the icing sugar and 1/2 tsp salt. Using a knife or a processor, cut the butter and cream cheese into the flour mixture until it resembles coarse breadcrumbs.
Add enough cream to mix to a soft dough. Gather into a ball and knead very briefly to smooth it out. Divide dough into 2; wrap each in cling film and chill for at least an hour.
Lightly grease your bun tins. On a lightly floured surface roll out the pastry to the thickness of a coin, then stamp out equal numbers of 6cm and 7cm circles. Roll up the offcuts, knead lightly, and then roll out again.
Use the larger circles to line the cups of the tins. Place a heaped tsp of mincemeat in each cup, cover with the smaller disc and lightly press together. Make a small hole in the centre of each lid for the steam. Chill for 30 minutes before baking.
Heat oven to220/gas 7 and place a baking sheet in the oven to heat up (the intense blast of heat to the bases helps them to cook through more effectively).
Bake for 10 minutes approx; reduce heat to 180/gas 4, then cook another 10 minutes, until golden brown. Brush lightly with milk, dust with caster sugar, and then return to the oven for approx 1 minute.
Cool in the tins for 5 minutes, and then ease out. These will freeze for up to 3 months!