If you want to get a head start on your Christmas baking, you can certainly make this in advance. After the cake has cooled (before icing) wrap it in 2 layers of plastic wrap and then 1 layer of aluminium foil and freeze. To defrost let come to room temperature on the kitchen bench overnight while still wrapped. From here, simply make your glaze and the cake will be just like fresh. Alternatively if you have left over cake you can wrap slices individually in plastic wrap and place in a ziplock bag in the freezer and just take a slice as you need it, again letting come to room temperature in the wrapping before serving.