The semi-final sees Benoit Blin and Cherish Finden joined by Gabriella Cugno - world-renowned official chocolatier for the movie, Wonka - as the contestants are challenged to produce two types of chocolate bars fit for the silver screen. After that, in what might be the toughest challenge ever set, the teams must create an entirely edible 'floating cities' showpiece that floats on water, embellished by 24 petit fours.