Clean and wash Brussels sprouts. Cover and simmer in approx. 3/8 l boiling salted water for approx. 15 minutes. Dice the ham. Rasp cheese. Drain the Brussels sprouts. Catch the vegetable water. Heat the fat. Sweat the flour in it while stirring. Stir in milk and vegetable water. Bring to the boil and dissolve the broth in it. Simmer for approx. 5 minutes, stirring frequently. Melt 100 g cheese in it. Season to taste with salt, pepper and nutmeg. Put Brussels sprouts and ham in a greased baking dish. Pour sauce over it. Sprinkle with the rest of the cheese. Bake in a preheated oven (200 ° electric stove) for about 40 minutes until golden brown.