Preheat the oven to 190oC/374oF (with the convection off).
Mix the dry ingredients together in one bowl and all the liquid ones – in the other.
Add the wet ingredients to the dry ones and wait a bit until baking soda and sour cream react with each other.
Your oven is already hot? Great! Pour the dough into a cake mold and bake for 30-40 minutes.
Check the readiness of the biscuit: a toothpick or a match should come out dry. Cool the biscuit down on a wire rack.
For the cream filling, take the cold butter out of a fridge and cut it into small cubes. Put them into a bowl, add some erythritol powder and start blending! The mass will get lighter and smoother. Add some vanilla extract and blend again, then some cream cheese and blend again.
Carefully cut your biscuit into three (or more) layers, depending its height. Cover each layer with the cream. Choose anything your heart desires for the top of the cake: it could be berries, extra cream, biscuit crumble, or even little cream roses if you can master
them.
Let your cake cool down in the fridge for at least three hours, optimally overnight.