The cake must be elaborate—and white

While there is no official rule on this per se, royal wedding cakes have followed a familiar recipe. For decades, guests have been served a traditional English fruitcake. The towering creation is frosted in white and decorated with elaborate piping in the shape of flowers and often the couple’s initials.

William and Kate had two cakes at their reception: the multi-tiered fruitcake and a chocolate biscuit cake that was specially requested by William. Meghan and Harry will be serving guests a lemon elderflower cake which may or may not be decorated with real flowers from the grounds at Windsor. Harry is a big fan of bananas, so it won’t be a surprise if he has his own banana groom’s cake.