After the big day, the top layer of the cake is traditionally stored away to serve at the Christening of the couple's first child
Credit: Thomas Northcut/Getty; Inset: Tim Rooke/Rex

Banana flan may take the cake as Prince William‘s favorite dessert, but there’s another sweet treat that wedding guests will be digging their forks into at the April 29 royal affair: Pass the fruitcake.

Sarah Haywood, a British wedding designer, tells PEOPLE the dessert is a U.K. wedding staple with its own traditions. Couples usually store the top layer of the cake in a tin and serve it at the Christening of their first child, she says.

“Someone has told me that in America, they are astonished that we eat fruitcake,” Haywood tells PEOPLE. “Americans do not get fruitcake.”

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And whether or not the dessert takes off in the states, fruitcake, usually made with candied fruit, nuts, spices and, sometimes, a layer of icing, fruitcake may already be on the top of the menu at the regal wedding – literally.

“Each tier [of the cake] will be different,” Haywood says of one current trend, “and we usually put the fruitcake at the top.”