Wash the potatoes and cook in boiling water for about 20 minutes. Wash the meat, dab dry and cut into 8 medallions. Heat oil in a pan. Brown the meat on both sides.
Remove and season with salt and pepper. Peel and finely chop the onion. Sauté onion in frying fat and deglaze with stock, cream and calados. Bring to the boil briefly and thicken with sauce thickener. Drain potatoes, quench, peel and cut into thick slices.
Grease a casserole dish. Layer potato slices. Put medallions on top. Pour the sauce over them and sprinkle with cheese. Wash thyme, dab dry, remove leaves and sprinkle over cheese.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Lamb's lettuce tastes good with it.