From the butter and flour make a light roux, which is diluted with cold milk and boil, stirring constantly, until get very thick sauce. The sauce was cooled to room temperature. Add grated cheese and egg yolks one by one. Egg whites are broken down into hard snow and added carefully with a wooden spoon. Sprinkle salt and pepper to taste. Soufflé pour into well oiled higher form (can high pot). Raw mixture should fill only 1/3 of the court. Bake in the middle of the oven at 220 C within 50 minutes. Serve hot. Optional in the mixture before baking can add finely chopped ham or stewed mushrooms, or both.