Heat oven to 160C/140C fan forced. Grease the two cake tins with Nuttelex, then line the bases with baking paper.
Process in blender until smooth 1 large avocado and 300g brown sugar.
Add 350g gluten-free plain flour, 50g cocoa powder, 1 tsp bicarbonate of soda, 2 tsp gluten-free baking powder, 400ml unsweetened soy milk, 150g Nuttelex and 2 tsp vanilla extract to the bowl with a pinch of salt and process again until smooth and lump-free.
Divide mixture between the tins and bake for 25 mins or until fully risen and a skewer inserted into the middle of the cakes comes out clean.
Cool in the tins for at least 10 mins, then turn the cakes out onto a rack to cool completely.
Next, prepare the frosting. Beat together 85g ripe avocado and 85g Nuttelex with electric beaters until creamy and smooth. Pass through a sieve and set aside.
Melt 200g vegan chocolate, either over a bowl of water or in the microwave, then let it cool for a few mins.
Sift 25g cocoa powder into a large bowl. Bring 125ml unsweetened soy milk to a simmer, then gradually beat into the cocoa until smooth. Cool for a few mins.
Add the avocado mix, 200g sifted icing sugar, melted chocolate and 1 tsp vanilla, and keep mixing to make a shiny, thick frosting. Once the cakes are completely cooled, use the frosting to sandwich the two cakes together and for the top.