I would put icing sugar in the cream for the outside and pipe it on the outside (after a thin layer of white) using a zip log back and make big long piped lines in green and red so it looks like a huge candycane. Then you could dust with icing sugar or cachous. Or you could make a yule log by melting some choc and mixing with the cream (when cooled) like you would to mousse and covering the ripple cake and scoring with a skewer to look like wood and then dust with icing sugar. Decorate the plate/board with some broken candy canes.

Ditto Rivlas
ooh, i like the candy cane idea! gonna have to find me a piping bag tomorrow i think (migth actually pop down the street tonight - i loathe the idea of shopping on Christmas Eve