Preheat the oven to 180°C (356°F).
Melt the dark chocolate and butter together using a double boiler.
Add erythritol to the melted chocolate and butter, and mix well.
Add the egg and mix.
Add almond flour, cocoa powder, baking powder, and salt, and make a dough.
Shape the dough into balls and place them on a baking sheet.
Bake in the oven at 180°C (356°F) for 12-15 minutes.
Let cool before serving.