It's made with quality chocolate rather than just cocoa powder and it is all the better for it.
I don't remember where I got the recipe from, I scribbled it down a long time ago but I do know it's definitely the easiest frosting I've ever made and is so yummy...
50g dark chocolate (with over 70% cocoa content)
200g icing sugar
1 teaspoon of vanilla extract
A little milk to loosen
Melt chocolate in bowl over water and then allow to cool until the chocolate no longer feels hot to the touch.
Beat butter in a bowl until a soft then beat in the icing sugar. Add in vanilla and beat again.
Fold in melted chocolate, adding a little milk if mixture is too stiff.
* To use as cake 'topping', place in a tub in the fridge for 24 hours, then take out for an hour to soften. Use electric whisk to soften further.