I found the cake task yet another daft one. There are businesses out there who design cakes for such an event and surely a restaurant would just buy one in. I can't see there is a professional cake designer in every restauarant.
The couples were specifically told the cake had to be made by the chef - under no circumstances were FOH allowed to help in any way
It was also not an option to refuse the cake - as this would have resulted in a failed task