Preheat the oven to 180°C.
Melt the dark chocolate and butter together using a double boiler.
Put the eggs and erythritol in a bowl and mix well.
Add the melted chocolate and butter mixture and mix again.
Add almond flour, baking powder, and salt to make the batter.
Pour the batter into a pound cake mold.
Bake in the oven at 180°C for 20 minutes.
Let it cool before eating.