These are fantastic: a real improvement on basic mince pies and the ice cream works well with hot mulled wine! It's best to make the meringue and to brown it as close to the time when you want to serve the pies as possible.
Preheat the oven to 180ºC/350ºF/gas 4. Dust a clean work surface and rolling pin with flour, and roll out the pastry until it is a little thicker than a £1 coin – about 4mm thick. Carefully cut out 10 circles of pastry large enough to line 7–8cm individual fluted tart tins. (Alternatively, cut out smaller circles and line a 12-hole bun tray.)
Spoon the mincemeat into the pastries and bake for 20 minutes, until cooked through and golden, and the mincemeat is bubbling hot. Set aside on a wire rack to cool completely.
In a clean bowl, whisk the egg whites with 1 tablespoon of caster sugar until it thickens and you have stiff peaks. Gradually whisk in the rest of the sugar and keep whisking for a few more minutes until the meringue turns thick and glossy.
Cover each mince pie with a shallow scoop of ice cream and then top with a dollop of meringue. Fork the meringue up a bit so it gets little peaks all over it, then brown briefly under a hot grill before serving.