Place the ready-made custard and
mascarpone or sour cream in a bowl, and beat until smooth. Divide a
third of the sponge finger biscuits among four parfait glasses and
sprinkle with a third of the sherry. Spoon a third of the custard and
mascarpone mixture over the sponge biscuits and scatter with a third of
the raspberries. Repeat all the remaining ingredients to make three
layers in total, finishing with the raspberries. Refrigerate for 1 hour
before serving.
