Put the dried cranberries, apple, mixed dried fruit, sugar, spice and sherry or ginger wine in a food processor and blend briefly until the ingredients are finely chopped but not puréed. (Or, chop the fruits as finely as possible before stirring in the other ingredients.) Stir well, then cover and leave to stand for several hours or overnight.
Place 16 mini silicone muffin cases on a baking sheet. Put the butter, sugar, flour and whole egg in a bowl and beat with a hand-held electric whisk until light and creamy. Divide among the cases. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 10–12 minutes, or until risen and just firm. Leave to cool in the cases, then transfer to a wire rack. Scoop out a little from each centre and pile the mincemeat and juices on top.
Make the frosting by putting the egg whites, icing sugar and cream of tartar into a thoroughly clean heatproof bowl. Place the bowl over a pan of gently simmering water, making sure the base of the bowl does not rest in the water. Whisk using a hand-held electric whisk for about 5 minutes until beginning to thicken. Remove from the heat and whisk for a further 4–5 minutes for peaks. Pipe or spoon the frosting over the cupcakes, swirling with a palette knife to form soft peaks.