Makes 8 portions.
225g (8oz) butter, at room temperature
325g (11oz) dark muscovado sugar
4 eggs, beaten
225g (8oz) plain flour
2 tsp baking powder
2 heaped tbsp cocoa powder
400g (14oz) raw beetroot, finely grated
85g (3oz) grated dark chocolate (minimum 70% cocoa content)
bsp vanilla essence
icing sugar, to decorate
23cm (9in) deep-sided cake tin, greased