Clean the mushrooms, possibly wash and halve them. Clean, wash and cut leek into rings. Dab meat dry. Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Heat oil in a large pan.
Brown the meat in it in portions on each side for 1 minute. Remove. Sauté the mushrooms in the hot frying fat. Fry the leek. Deglaze with cream and bring to the boil. Season to taste with salt and pepper.
Put the steaks in an ovenproof dish, season. Add creamed vegetables. Grate cheese on top. Bake in a hot oven for about 10 minutes. Sprinkle with nuts. Serve with bread.