Heat a pot of water and melt the chocolate and butter in a water bath.
In the meantime separate the eggs, add the sugar to the egg yolks and whisk until dissolved. Add the melted chocolate to the egg yolks and mix well. Gently stir in the flour, whip the egg whites and fold in carefully.
Butter the ramekins, coat them with sugar and fill three-quarters full with the soufflé mixture.
Put them on an indirect zone of the grill, close the lid and cook for 8-10 minutes at 200°C / 392°F.
Dust the finished chocolate soufflés with icing sugar and enjoy.