Combine together erythritol and cocoa powder. Put the bowl aside.
Beat the eggs in another bowl until soft.
Pour the beaten egg into the erythritol and cocoa powder. Add melted butter, baking powder, vanilla, and cream into the mix as well. Stir together then flavor with a pinch of salt.
Cover your mixture with parchment paper or use silicone cake pan and distribute base mix on the bottom of your pan. Bake for 10-15 minutes in a preheated oven.
Use a mixer to whisk together all filling ingredients. Pour the filling on top of the baked base.
Reduce the heat to 300 degrees F, return the cake into the oven and bake for 20 minutes more.
After removing from the oven, allow to cool at room temperature and chill in the fridge for 6 hours or overnight.
Cut into slices and serve drizzled with melted chocolate (optional).