This impressive rainbow cake is the perfect celebration ... Put a dab of buttercream on the cake board and place the purple sponge on top. Spread a ¾cm/½in thick layer of buttercream on the ...

It is a great cake to make for a street party, sporting event or royal knees-up. If you bake the sponge ahead, wait until the day you're serving it to add the fruit for the freshest appearance.