Heat 1 tablespoon of oil in a pan. Fry the meat sausage and onions in it. Put in a greased baking dish. Then fry the Brussels sprouts and the gnocchis one after the other. Season the Brussels sprouts with a little nutmeg. Put both in the baking dish and mix everything well. Season everything with a little salt and pepper. Preheat the oven to 200 ° hot air.
At the same time, prepare a light sauce (bechamel sauce) that is not too thick. To do this, melt the butter, add the flour, sweat. Deglaze with 125 ml Brussels sprouts stock and 250 ml milk. Let simmer for a few minutes. Melt about 50 g of the cheese in the sauce.
Now distribute the sauce evenly over the mixture in the baking dish. Then the cheese.
Gratinate in the oven for approx. 15 - 20 minutes, depending on the degree of browning you want.
Sprinkle with parsley and serve.