Place the chocolate and butter together in a bain marie, over a barely simmering heat and stir occasionally until they melt. Set aside to cool for a while. Whisk the eggs and the sugar together in a large bowl until they rise. Add the cool, melted chocolate, a little at a time, constantly stirring.
Sieve the flour and salt together into the mixture and fold it gently. Grease with butter and dust-flour very well 12 ramekins. Shake to remove the excess flour. Divide the mixture equally into the ramekins.
Bake at 200ºC for 9-10 minutes. Remove from the ramekins and serve instantly with crème fraîche or ice cream.