lightly dressed mixed baby salad leaves, to garnish
Preheat the oven to 190ºC (375ºF/Gas 5) and butter four ramekin dishes well. Slowly melt the butter in a heavy-based pan over a low heat. Remove pan from the heat and beat in the flour to form a smooth, shiny paste. With the pan back on the heat, add the milk and whisk to form a smooth sauce. Once the sauce has thickened, remove from the heat and leave to cool for a few minutes.
Add the egg yolks to the cooled sauce with the chives and a little seasoning and beat thoroughly to combine. Be careful not to do this when the mixture is too hot or the eggs will start to cook. Place the egg whites in a separate bowl and beat until lightly and fluffy, then fold into the sauce mixture, taking care not to lose the air.
Pour the mixture into the well-buttered ramekins and bake for about 25 minutes. Check at 20 minutes to ensure that the tops don't brown too much. Once they are done, leave for a couple of minutes in the ramekin dishes and then carefully take them out and leave on a baking sheet. (At this point you could leave them in the fridge once completely cooled and covered in clingfilm for a day or so, or you could freeze them.)
When you are ready to bake the soufflés for a second time, preheat the oven to 160ºC (325ºF/Gas 3). Mix together the crème fraîche or cream with the cheese, then season to taste. Carefully make a small well in the top of each soufflé and spoon in a couple of teaspoons of the cheese mixture. Pop into the oven for at least 10 minutes until the cheese has melted. They can be kept warm at 130ºC (250ºF/Gas 1/2) for up to 30 minutes, but no longer as they start to dry out and go rubbery.
Transfer to warmed plates with a fish slice and spoon any resulting sauce on top, then garnish around the plates with the lightly dressed mixed baby salad leaves.