Combine flour, butter, sugar, eggs and cocoa powder and beat or use an electric whisk. Turn mixture into a greased cake tin. Bake for 1 hour in the preheated oven.
Meanwhile, make the icing by combining the butter and icing sugar. Beat until smooth. Add vanilla and stir. If needed add a teaspoon of milk at a time to achieve your desired consistency.
Cool the cake, then slice in half to make two layers. Spread a thin layer of butter icing in the middle. Add fresh fruit if desired. Place cake layer on top to make a sandwich. Spread more butter icing over the top and sides of cake.
Cut the chocolate fingers different lengths and stick along the sides of the cake till covered.
Sprinkle the white and milk chocolate shavings over the top. Serve.