Melt the butter in a pan, add the flour and mix well using a whisk. Cook on a low heat for a few minutes, but do not let it brown. Take the pan off the heat and gradually add the milk while continuously stirring. Once the ingredients are combined into a smooth mixture (similar to pancake dough consistency), turn up the heat and bring to a simmer. Cook for 5-10 minutes on a low heat while stirring with a whisk. Add the pepper and grated nutmeg. While the sauce is on the stove, grate the cheese. Gradually add the cheese to the sauce, and keep stirring until it is a smooth mixture.
Now it is time to whisk the eggs. Carefully separate the yolks from the whites. Whisk the whites with a pinch of salt until they form stiff peaks, firm enough to keep their form when the bowl is turned upside down.
Take the sauce off the heat and add the mixed yolks. The mixture should be warm, but not hot, to keep the yolks runny. Add a third of the egg whites and stir lightly. Pour the mixture into a bowl and add the rest of the whisked whites. Stir carefully.
Coat heat-resistant baking dishes with butter, sprinkle the inside with grated cheese, and fill them halfway with the prepared soufflé mixture. Place into a pre-heated oven and bake for ~ 30 minutes. Do not open the oven door while the soufflé is baking.
The soufflé is ready when it has doubled in size and is a fine golden colour.