Preheat the oven to 180C/Gas Mark 4 and lay out 12 cup cake cases on a baking tray.
Using an electric mixer, mix the butter, sugar, flour and cocoa powder in a bowl adding the beaten eggs slowly into the bowl as you are mixing.
Using a large spoon place equal amounts of mixture into the 12 cupcake cases. Place in the oven (near the top) and bake for 15 to 20 minutes – until firm to touch.
Remove from the oven and leave to cool.
Place the butter into a bowl, stir in the icing sugar and vanilla extract using a wooden spoon, then whisk until fluffy.
Then spread the buttercream onto the cakes with a warm spoon or for a more proffesional look put the icing into a piping bag and squeeze plenty onto each cupcake.
Decorate using chocolate curls. To make the curls take a vegtable peeler or a cheese slicer and run it along the chocolate until you get proffesional looking chocolate decorations
Tip
Make sure your cupcakes are completely cool before adding the buttercream icing