For the bottom: mix 120g almond flour with 30g cocoa powder, 60g erythritol, 1 tsp baking powder, pinch of salt and vanilla, 1 egg and 30g melted butter. Bake for 20-25min in a 175° oven (keep a close eye on it - every oven is different). You can make the bottom perfectly in advance and keep it in the fridge.
Once your bottom is completely cooled off you can start "decorating" it.
For the chocolate sauce: heat 30ml full cream in a pan over medium heat. Then add half a tablet of Okono chocolate (25g), 1 tbsp of erythritol, vanilla powder and 1 tbsp of butter. Keep stirring until everything is melted.