The Groom’s cake tradition is normally associated with South America; however in the UK the Groom's cake is a tradition dating back to Victorian times. Unlike a wedding cake, a Groom’s cake can be of various shapes, colours, sizes and textures. The Grooms cake is served at the wedding reception or rehearsal dinner. If served at a wedding reception, it's usually located on a separate table to the main wedding cake.
Here is an impressive example of a Grooms Cake from the Cake Parlor in Wimbledon
Image curiosity the Cake Parlor