Clean the mushrooms and wash them if necessary. Unscrew and chop stalks. Peel and dice the onion. Wash and chop the parsley.
Put the oil in a pan and fry the mince vigorously. Sauté the onion and mushroom stalks. Stir in the parsley. Take everything out and set aside.
Bring the tomatoes and cream to the boil in the frying fat. Season with salt, pepper and marjoram.
Fill the mushrooms with the mince and place in a baking dish. Spread any remaining filling around it. Pour the tomato sauce over it and rub the cheese over it.
Bake in a hot oven (200 ° electric stove) for 25 - 30 minutes.