Chocolate Lace Crisps

I made these for a cake sale at work today to help a very worthy local cause.  It is an Australian recipe - they are such good bakers!  They were a nice texture - crisp on the outside, a little chewy within, and very chocolatey.  A bit sweet for my taste, though - I will experiment with 150g of sugar rather than the 220g.  The success of the crackled 'lacy' surface does depend on a thick coating of icing sugar before they are baked.  A pretty biscuit and worth trying again.
The recipe, taken from Australian Women's Weekly's 'tray bakes and slices':
100g dark eating chocolate, chopped coarsely
80g butter, chopped
220g caster sugar
1 egg
150g plain flour
2 TBSP cocoa powder
¼ tsp bicarbonate of soda
¼ cup (40g) icing sugar
Melt the butter and chocolate in a large bowl over hot water or carefully in the microwave, add all the other ingredients (except icing sugar) and mix until combined.  Cool in the fridge for 20 minutes.  Line 2 baking sheets with parchment and set oven to 180C.  Take flat dessertspoons of the mix and roll into balls.  You should get around 26 biscuits.  Roll each ball well in icing sugar and place on the baking sheets, spacing well apart.  Don't flatten them.  Bake for 15 minutes.  Leave to set and cool on the baking sheets.  Eat.  Go and lie down after the sugar rush.  Eat some more.