Cake can be iced up to a week in advance. If eating decorations, keep gingerbread trees in their containers and add to cake on the day.
Cover the cake with jam, marzipan and ready-to-roll icing), taking the icing to the edge of the board.
To decorate, roll out several marble-sized balls of the 100g ready-to-roll icing to make snowballs, then set aside. Roll two larger balls, one a little bigger than the other, to make the head and body of the snowman, then leave to dry for at least 30 mins.
Meanwhile, ice the gingerbread trees. Beat the egg white with the icing sugar to make a smooth paste. Put about one-third of the icing into another bowl, then mix in a speck of green colouring and a few drops water so that it’s fairly runny and very pale green. Spread this over three of the gingerbread trees and leave to dry. Spoon another third of
the icing into a piping bag fitted with a fine writing nozzle. Pipe rough fir-tree-like branches over the remaining trees. Once the green iced trees have dried to the touch, pipe branches over those, too.
When the icing has set, fix the trees onto the cake and around the edge using spots of the remaining thick royal icing. Put the smaller snowballs around and on top of the cake. Pipe eyes and a mouth onto the head of the snowman and insert the nose. Fix the snowman’s head on with a spot more icing, position him on the cake, then carefully tie a ribbon scarf with the shorter length of ribbon. This is easiest if you start with too much ribbon, tie it, then trim with scissors. To finish, attach ribbon around the base and secure woth a double-sided tape.