In a large mixing bowl combine coconut sugar, spelt flour, cake flour, cocoa, beetroot powder, baking soda and baking powder. Start beating with the mixer at a very low speed, until the ingredients are blended. Gradually add the eggs, oil and vanilla and continue beating, increasing the speed just a bit. At the end add the buttermilk, mixed with the vinegar. Beat just until all ingredients are combined well and the batter is smooth. Do not overbeat!