550g icing sugar, sifted
250g butter, softened
100g 70% cocoa dark chocolate
2 tbsp milk
4 X 135g packets of maltesers to decorate (or 2 jumbo packets)
Preheat oven to 180 degrees (160 if fan forced).
Using an electric mixer or food processor, mix sugar, butter, flour, sour cream, eggs, baking powder, cocoa powder, salt and vanilla in a large bowl until smooth.
Divide mix evenly between 2 lined and greased 2X20 cm round cake tins.
Bake for 25 - 30 mins or until a skewer comes out clean when inserted into the centre of each cake. Turn onto a wire wrack to cool completely.
Begin the icing by melting the chocolate (easily done in microwave using 30 intervals, stirring well until smooth).
Sift icing sugar into a medium sized bowl, add butter and milk and mix (with an electric mixer) until combined. Add melted chocolate and continue to mix until smooth.
Spread a 1.5 cm layer of icing over the top of one sponge, then place the second sponge on top.
Use the rest of the icing to cover the cake completely, ensuring it is evenly spread and smooth.
To decorate the cake, start by placing a single line of maltesers along the centre of the cake, beginning at the base of one side and finishing at the base of the opposite side. To ensure coverage is even, form the next line directly beside the first. Continue this until the cake is totally covered. (Tip: wearing cotton gloves for this step helps to avoid melting or making fingerprints in the maltesers).