For the party I whipped up a quick sponge cake, you could easily use a bought sponge and just decorate it. To make the North Pole sign I used a sweetie tube, the Japanese equivalent to smarties, we had used the sweets on the gingerbread houses. I covered it with white paper then used red tape to make the stripes. The actual sign was just a piece of card then I stuck it to the pole. Then jammed the whole thing into the centre of the cake.
Next, make the royal icing, 2 egg whites (should be at room temp), 1/4tsp cream of tarter and 2 1/2cups of icing sugar, whisk until thick. Pour all over the cake, add a few mini marshmallows for snowballs and I happened to have some snowflake sprinkles so I threw them on too. Finished it off with by dripping icing on the sign and some chocolates that were wrapped as presents.