Cut the sponge in half and fill with jam, then cut it into large cubes and put into a glass bowl. Use a nice bowl that can be seen through so the layers are visible.
Spoon sherry or liqueur over the sponge, then lay out the fruit on top. If there is any juice, pour over the top.
Mix the custard powder, sugar and ¼ cup of the milk to a smooth paste. Add the remaining milk and cook over a low heat, stirring constantly until mixture boils and thickens.
Remove from the heat, cover and leave until cool, then pour the custard over the fruit. Chill for 1 hour then cover with whipped cream and toasted almonds, or other decorations. If you’re feeling traditional, put the cherry on top!