Melt the chocolate with the butter. Beat the eggs with the sugar in a deep container.
Mix together the melted chocolate (and butter) with the eggs and sugar.
Lastly, add the flour and stir well. Distribute the mixture into muffin forms.
Put a piece of chocolate in the middle of each muffin (optional). Bake in a 365°F (185 °C) oven about 15-20min.