Preheat oven to 175C/350. Grease an 8 inch (20cm) cake tin.
Sift the coconut flour, cocoa, baking powder and baking soda in a small bowl. Add the salt and set aside.
In the bowl of a stand mixer with whisk attachment, whisk the eggs for 5 minutes, or until fluffy.
Meanwhile, palce the beetroot and the milk in a blender and puree until cmobined. Alternatively this can be done with a stick blender.
Add the beetroot/milk mix, maple syrup, vinegar and vanilla extract to the eggs and continue to mix until combined.
Add the dry ingredients into the wet ingredients.
Mix on low speed until the dry ingredients are incorporated – about 30 seconds. Scrape down sides of mixing bowl (you may need to do this a couple of times) and beat cake batter on medium/high speed for about 1 minute so that the batter is fluffy.
Pour the batter into the tin and smooth out the top. Bake for 35 minutes or until a toothpick inserted in the centre comes out clean. Allow the cake to cool in the tin before removing and frosting.