Melt the butter in a saucepan over a low heat, add the flour and stir continuously for 1 minute. Remove from the heat and gradually add the milk, whisking until smooth. Return the pan to a low heat and bring to the boil, stirring continuously, then reduce the heat and simmer for a further minute. Allow it to cool slightly before beating in the egg yolks. Fold in the flaked fish.
Whisk the egg whites until they form firm peaks, then fold them into the fish mixture. Gently spoon the mixture into 4 lightly buttered ramekins or moulds (fill them about three-quarters full). Place the filled moulds in a roasting pan and fill this with boiling water until it comes one-third of the way up the sides of the ramekins. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 12–15 minutes, or until set, then remove from the oven and the water and leave to cool.
Unmould the soufflés and place in either individual serving dishes or 1 large dish. Pour over the cream and return to the oven for a further 10 minutes until hot.
Top with a little more flaked fish before serving with some Lemon Hollandaise Sauce (see below).