For the gratin, peel and wash the potatoes and slice them into thin slices. Rub garlic into an ovenproof dish, layer the potatoes in flakes and season with salt and pepper.
Sprinkle with cheese and pour 200 g cream over it. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for approx. 45 minutes. In the meantime, wash the fillets and pat them dry. Place the bacon slices next to each other.
Place the fillets on top, roll them up and pin them with chopsticks if necessary. Fry for approx. 12 minutes, turning over. Season with salt and pepper. Deglaze with 1/4 litre water and bring to the boil. In the meantime peel and finely dice the onion.
Clean, wash and chop the mushrooms. Fry in hot fat. Wash, chop and add parsley. Cut fillets into thick slices. Spread the mushroom mixture on top. Just before serving, put them in the oven for 5-7 minutes for gratin.
Peel and slice the carrots. Clean the savoy cabbage, cut out the stalk. Cut the savoy cabbage first into slices and then into thin strips. Cook the vegetables in boiling salted water for about 8 minutes and drain.
Bring the gravy and the rest of the cream to the boil and cook the vegetables for another 5 minutes. Sprinkle in sauce thickener. Season to taste with salt, pepper and orange juice. Serve everything garnished with oranges and parsley.