Chocolate Beetroot Cake

1 1/2 cups plain flour
1/2 cup cocoa powder
1 1/2 cups caster sugar
1 1/2 tsp baking powder
I cup veg oil
1 tsp vanilla essence
3 eggs
1 cup cooked beetroot, pure'ed 
2 Tbs walnuts, finally chopped (optional)

Sift all dry ingredients, add oil, vanilla, lightly beaten egg, beetroot and walnuts. Mix well (will turn a purple colour). Pour into a 7" square tin lined with paper. Bake at 180C for 50mins. When cool, dust with icing sugar.