Peel and wash the potatoes, halve or quarter them depending on size. Cook in boiling salted water for about 20 minutes. Dab meat dry, season with salt and pepper. Heat oil in a large pan. Fry the meat for approx. 4 minutes, turning it over. Take out and let it rest
Savoy cabbage clean, wash, halve and cut in short strips from the stalk. Peel and chop the onion. Heat the fat in a pot. Sauté the diced onion for about 5 minutes. After about 2 minutes add cabbage. Deglaze with broth and steam in a closed pot for about 5 minutes. Wash the thyme, shake dry, remove the leaves from the stems and add to the cabbage, except for a little bit for sprinkling
Roughly grate the Gouda, whisk with cream. Cut the meat into about 12 medallions. Cut mozzarella into 12 slices. Cover each medallion with 1 slice of cheese and wrap 1 slice of bacon around it
Spread the cabbage, potatoes and meat in a greased casserole dish. Pour cheese cream over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 45 minutes. Sprinkle the finished gratin with the remaining thyme
Leave the pudding to cool for at least 2 hours.