Place the cake on a clean board. Lightly dust a work top with icing sugar (dust your rolling pin, too) and roll out the sugarpaste into a circle no thinner than 5mm and slightly larger than the diameter of the cake and sides.
Lift the sugarpaste with your hands or loosely wrap it around the rolling pin, place it over the cake and gently smooth around the sides, covering the cake. Do not stretch the sugarpaste and work as quickly as you can, as it will dry out fairly quickly. Cut away any excess and seal it in a polythene food bag at room temperature for future use (providing it doesn’t have fudge icing on it). Smooth the top and sides all over with the palms of your hands; any lumps, bumps or blemishes can hopefully be removed now.
Arrange the sweets randomly over the surface of the cake, with the jelly beans around the base, sticking them all on with the royal icing.