"This sponge cake could also be made in a 7 inch (18 cm) tin (just use two eggs and 4 oz/115 g each of flour, sugar and butter). It can then be filled with jam and cream. And while the soft fruits of summer, when they're available, are perfect for filling sponge cakes, in winter, passion fruit fulfil all the criteria needed, ie, something sharp, fragrant and acidic to contrast with the richness of the cake and cream...."