Sift almond flour and sweetener together.
Mix baking powder, egg, milk, melted butter, and a drop of vanilla.
Microwave for 2 minutes (adjust time as needed while watching).
Combine egg yolk and sugar, then mix in mascarpone and vanilla.
Brush the cake layer with coffee dissolved in 20ml of water.
Spread the cream on top, cover with wrap, and refrigerate for 6 hours.