Place a baking tray on the bottom shelf of the oven. Preheat the oven to 200°C.
Egg yolk mixture
Heat the butter in a small pan. Add the flour, cook while stirring; the flour must not take on any colour. Remove the pan from the heat. Bring the milk to the boil with the nutmeg and salt. Pour through a sieve into the flour, stir to form a thick paste which separates from the base of the pan, allow to cool slightly. Gradually add the egg yolks, stirring until smooth. Stir in the cheese.
Beat the egg whites with the salt until semi-stiff. Beat approx. 1/3 of the egg whites into the egg yolk mixture using a whisk, then carefully fold in the rest using a rubber spatula. Transfer to the prepared dishes. Place the dishes on the hot tray in the oven.
Approx. 25 mins. in the preheated oven. Do not open the oven, otherwise the soufflés will collapse. Remove from the oven, serve immediately.