Wash the potatoes and boil in water for about 20 minutes. Then quench, peel and let cool
Clean, wash, quarter and cut the savoy cabbage into wide strips. Peel and finely dice the onion
Heat the oil in a large frying pan. Sauté the onion in it until transparent. Add cabbage and fry for 6-8 minutes, turning. Season with salt and pepper
Heat the fat in a pot. Sweat flour in it. Sprinkle with paprika. Stir in 1/4 l water, milk and stock. Bring to the boil and simmer for about 5 minutes. Season with salt, pepper and sugar
Cut the potatoes into slices. Layer with savoy cabbage and sauerkraut in a greased ovenproof dish, finishing with potatoes. Spread the sauce and cheese on top. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for 30-40 minutes