This recipe is a lot easier than Nigel Slater's one that Ginny made, even though it's probably not as decadent. But I added jam and cream for a special birthday treat. I like that the beetroot is added in raw, you don't have to precook.
This is adapted from the NZ Woman's Weekly.

1 c brown or muscovado sugar
1 1/2 c vegetable oil
4 eggs
2 tsp vanilla essence
2 c 5flour
1 tsp baking powder
1 tsp baking soda
1/2 c cocoa
1 tsp salt
2 c raw beetroot, peeled and grated
Ganache: 
melt 125g dark chocolate, 1 tbsp butter and 1/3 cup cream together over a bain marie.

Preheat the oven to 180ºC. Grease and line the base of a 23cm spring-form cake tin with paper.
In a large bowl mix the 4first four ingredients well. Sift in the next five ingredients and fold into the batter
adding the beetroot along the way.
Pour into the tin and bake for about an hour, or until an inserted skewer comes out clean.
Cool in the tin, then turn out and cut cake into two layers. Spread bottom layer with jam and cream and place on the top layer. Cover with chocolate ganache.