Preheat the oven to 180°C (356°F).
Melt dark chocolate and butter together in a double boiler.
In a bowl, combine the eggs and erythritol, mixing well.
Add the melted chocolate and butter to the egg mixture and blend.
Sift in cocoa powder and almond flour, then gently mix until smooth.
Pour the batter into muffin molds.
Bake in the oven at 180°C (356°F) for 10-12 minutes.
Remove from the pan, allow to cool, and serve.