Grease and line the bases of two 18cm (7") sandwich tins with baking paper.
Pre-heat the oven to 190°C (fan 180°C).
Using a food processor, blend the eggs, sugars and oil together until thick and creamy. Remove to a large mixing bowl.
Chop the beetroot into a smooth puree in the food processor.
Add the cocoa powder and allspice to the beetroot and blend together.
Add to the egg mixture and stir together.
Sift the dry ingredients into the bowl, adding the vanilla extract and orange zest and fold with a metal spoon until well incorporated.
Divide the mixture between the two sandwich tins and bake for approximately 35 minutes, or until an inserted cocktail stick comes out clean. The cakes will be quite dark in colour.
Allow to cool on wire racks.
When completely cold, sandwich together with damson jam (approx ½ a jar).
Recipe courtesy of Samantha Park, winner of the Celebrity Bake Book competition.