Preheat the oven to 180 degrees C.
Line a cupcake tray with paper or foil cases. Sift together the flour, baking powder, bicarbonate of soda, cocoa and salt. Set aside.
In a large bowl, cream together the butter and sugar until light and fluffy. Add the eggs one at a time, beating well with each addition, then stir in the vanilla. Next add melted dark chocolate and combine.
Add the flour mixture alternately with the milk; beat well. Fill the paper cups 3/4's full.
Bake for 15 minutes in the preheated oven, or until a skewer inserted into the cake comes out clean. Ice when fully cool
Beat together the cream cheese and butter for a few minutes until pale and smooth. Add the icing sugar in two stages, beating well between each stage. Continue until it looks very smooth and shiny.
Divide the frosting into 4 bowls – you don’t need to measure it precisely.
Add a few of drops of different food colouring to each and mix well until you get the colours you want.
Take a piping bag an attach a nozzle. An open star or ruffled nozzle looks best for this icing.
Add in the coloured icing alternatively using tablespoons until you fill the bag.
(a spoon of pink, followed by black then purple, blue etc)
Before piping the icing onto the cakes, give the bag a squeeze till more than one colour comes out.
Hold the piping bag at a 90 degrees angle to the centre of the cake and squeeze until the icing reaches the edge of the cake.
Next keep squeezing and spiral the piping bag upwards in a circle until it’s a nice big swirl, then gently lift the bag away as you stop squeezing.
Finish by sprinkling some edible glitter and/ star sprinkles on top.