Pre-heat the oven to 180⁰C.
Line 2 cup cake trays with 18 paper cake cases (the small ones ie not muffin size).
Sieve the flour and cocoa into a bowl and add all the other ingredients.
Mix together with a wooden spoon until well mixed.
Spoon into the paper cake cases.
Bake on the middle shelf for 13 minutes or until an inserted skewer comes out clean or cakes spring back to the touch.
Allow the cakes to sit for a couple of minutes before transferring to a wire cooling rack.
To make the topping break the chocolate up into a glass bowl with the butter and melt it over a pan of simmering water stirring with a wooden spoon.
Use a teaspoon to decorate the cakes with the chocolate topping, giving a little swirl with the back of the spoon to spread it out evenly and then add a Smartie/sweet to finish.