Clean, wash and cut the cabbage into strips. Peel and finely chop the onions. Heat the oil in a pot, fry half of the onions in it. Add the cabbage, braise briefly and season with salt and pepper. Pour on 1/4 litre stock, add caraway and bring to the boil. Steam covered for about 10 minutes
Place the spaetzle in plenty of boiling salted water and cook until firm to the bite, stirring occasionally. Pour spaetzle onto a sieve, rinse under cold water and drain
Heat the fat in a pot and sauté the remaining onions. Add flour and sauté while stirring. Add 1/4 litre stock, milk and cream, stirring gradually. Bring to the boil and simmer for about 5 minutes. Stir in between. Stir mustard into the sauce and season to taste with salt, pepper, lemon juice and sugar
Place the spaetzle in a large, greased, ovenproof dish. Season savoy cabbage vegetables with salt and pepper and place on the spaetzle. Pour mustard sauce evenly over the spaetzle. Cover with bacon. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 30-40 minutes. Sprinkle with fried onions 10-15 minutes before the end of the baking time. Garnish as desired with an omitted crispy bacon slice