Peel and chop the onion. Heat the fat in a pot and fry the onion. Add the sauerkraut and braise over a high heat until it begins to brown. Deglaze with apple juice, add bay leaf and caraway and braise covered for about 10 minutes.
In the meantime, cut the pretzel rolls into 8-10 slices and place them on the grid of the oven. Roast in the preheated oven (electric cooker: 250 °C/ circulating air: 225 °C/ gas: level 5) for 3-5 minutes. Take out immediately and let cool down. Turn down the oven temperature (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2).
Halve the slices of liver cheese. Mix milk, cream and onion soup powder. Season the sauerkraut with pepper and a little salt and layer it together with the roasted pretzel rolls and Leberkäse in an ovenproof dish (approx. 2.5 litres capacity, 5 cm deep, 31 x 23 cm large). Pour the onion sauce evenly over it and sprinkle with cheese. Bake in a preheated oven for approx. 30 minutes. Garnish with parsley