This batter will make 2 x 20cm (base measurement) round cakes, which are sandwiched together by a thick layer of the icing, before being surrounded by icing in the “naked” fashion that is popular at the moment. If you prefer to use less icing, then you can simply sandwich the two cakes with a layer of icing, and then top the cake with icing alone instead of covering the sides too.
If you wish to do the sides, I have found the best way to get a nice even finish, is to place each cooled cake on a plate or cake board - with the base baking paper still on – double wrap it in Glad wrap and pop it into the freezer for at least two hours. This is sufficient time to “set” the crust of the cake, making it really easy to cover the cake with icing, and scrape around the sides thinly without collecting cake crumbs which can mar the final look of the cake. This is not absolutely vital, but just my suggestion based on what I have found.
The icing can be made and used straight away, or made in advance and kept for up to a week in the fridge, or at least a month in the freezer. The day you wish to use it, take it out of the fridge in the morning and place on your bench … keep it in its container until you are about to use it, and then stir through a spoon to loosen it up well enough to be able to spread over your cake. It should sit on your bench at least a couple of hours to loosen as it goes really firm in the fridge.
Once iced allow the cake to sit at room temperature for an hour or so to “set” the icing, then cover and leave at room temperature in a sealed container for 24 hours until ready to serve. Leftovers will keep in the same sealed container for a couple of days as long as the weather is not too hot, in which case I would put it into the fridge, but remove at least an hour before serving.
This is not a large cake, but the combination of the cake and icing is quite rich, so it is perfect for a group of 10 to 12 people. If you wish the cake to be larger, then I would suggest you bake the entire batter in a 24cm round tin, and make the cake 2 or 3 times based on how many layers you wish to have. Of course you will also then need to make more icing, but it keeps really well in the freezer which is what I do all the time, and can be a life saver.
When cutting the cake, if you wish to ensure a nice even slice, then dip your cake knife into a jug of hot water, wipe it clean with kitchen paper then cut each slice. Continue to “dip and wipe” as you cut each slice to give you consistent pieces … this will also allow you to cut thin pieces which can sometimes be quite difficult if your cutting knife is not “hot”.