Place a bowl over a saucepan of boiling water and slowly melt the dark chocolate.
Place the cream, cocoa powder, butter and erythritol in a small saucepan over a medium heat and slowly stir to combine.
Add the melted chocolate to the saucepan, stir to combine until the mixture has a thicker, glossy consistency.
Remove the saucepan from the heat and leave to cool for a minute before pouring over the top layer of the cake.
Serving Size 250g