Need an icing recipe for DDs birthday cake.

[petunia]

I've made DD a chocolate birthday cake this year. I've already cut it out into the shape of an 8 but need a nice icing to go on it. I think a chocolate icing will make the cake too rich but don't want one that's got so much sugar in, it'll make our teeth ache!
Any suggestions?
(Apologies for the typing errors, think it's a problem with apostrophes and Mumsnet!)

Except there only seems to be a problem when I "preview" my post!

If you don't want lots of sugary icing, why don't you just dust it with icing sugar from a height? it will just sprinkle the top nicely

What about a cream/ chocolate based one?

150 ml double cream
1 tsp unsalted butter
150g dark chocolate

Warm the cream & butter in a pan, add the chocolate, stir until melted, pour over cake.

It gets thicker as it cools and makes a really nice smooth, shiny icing.

Really easy & not too sweet.

The only thing you have to be careful of is making sure you put strips of greasproof paper around the edge of the cake. When you pour the icing on, it will run down the side of the cake onto the paper, which you can pull away when it has cooled.

Thank you for your suggestions. Not sure which one I'm going to use as they both sound nice!