Cake base Method
Preheat the oven to 180 degrees C fan
Mix flax egg thoroughly, ground flax and water and leave sit for 5 mins
In a large bowl mix dry ingredients, flour, coconut sugar baking powder, cacao powder
In another large bowl, mix wet ingredients, sunflower oil, non dairy milk, vanilla essence, soaked flax egg and mix really well so its homogenous.
Mix the wet ingredients into the dry ingredients till well mixed
Line an 8 inch springform tin with baking parchment on the bottom and also on the sides
Bake 180C Fan for 20 mins - rotate half way through.
Remove and leave to cool
Chocolate Mousse Method
Melt the chocolate over a bain marie; once melted add the oil and mix well, remove from heat and allow to cool a little but not start to harden, before adding to the whipped aquafaba.
Whip aqua faba with the vinegar or lemon juice using either a stand mixer or an electric mixer, until you have stiff peaks, this should take about 6-8 mins on almost full speed, add the sugar slowly on a slow speed, once all the sugar is incorporated, increase the speed back to high and continue to whip for about an extra 5 minutes until you have whats known as stiff peaks which means that when you hold the whisk up horizontally the whipped aquafaba mixter sticks to the mixer whisk.
Slowly add in the melted chocolate to the mixer as its running until all the chocolate is incorporated. Stopping the mixer to scrape down the sides of the bowl with a silicon spatula if necessary. Continue to mix for another 1 minutes, it will be a slightly runny batter.
Take the cooled cake still in the spring form tin and pour on this runny chocolate mousse. Add to the fridge and leave for 60 mins to set.
Option is to dust with cocoa powder before serving, slice (with hot knife to stop the mousse from squashing when slicing) and serve. enjoy