Set the oven to 170C/ 340 F You will need an 8 cup loaf tin or a 20 cm cake tin, lined with baking paper. You will need a food processor or stick blender
Drain the beetroot and put it in the food processor with the sugar. (The sugar will help the beetroot to puree). Process until the beetroot is a smoothish puree.
Add the eggs, oil, beetroot liquid and vanilla and process to combine
Sift the flour, cocoa and bicarbonate of soda into a bowl and pour over the beetroot mixture stirring until JUST combined. Don't overmix this cake
Pour into a lined sprayed loaf tin. Bake for 30 minutes. A tester skewer should come out clean. If the cake is not cooked, add 10 minutes to the cooking time.
Leave for 10 minutes in the tin then turn out onto a cake rack to cool