Boil up about 2 l salted water. Preheat oven (electric cooker: 200 °C/recirculating air: 175 °C/gas: level 3). Clean, wash and cut cabbage into strips. Clean mushrooms and halve them if necessary
Cook the spaetzle in boiling salted water for about 12 minutes. Steam cabbage in 1 tablespoon of hot fat for about 5 minutes. Season and take out. Heat 1-2 tablespoons of fat in the frying fat. Fry the mushrooms in it
Add approx. 1/8 l water and bring to the boil. Stir in stock and crème fraîche and season to taste. Drain the spaetzle. Layer everything in 4 small or 1 large casserole dish
Sprinkle cheese over it. Bake in the oven for about 10 minutes. Peel onion and cut into rings. Fry in 1 tbsp. hot fat until golden brown. Sprinkle on the cheese spaetzle