We are thinking of doing a similar and are going to do a basic white cake with a mirror or maybe some kitchen foil as a "frozen pond" inset into the icing.
We'll add a small model of a skater which you can either buy (with difficulty) or make out of sugar icing.
To make it kind of sparkly we are going to use some white tinsel to wrap round the outside of the cake. Any further tips from anyone would be welcome.
