Clean the mushrooms and cut into slices. Pat the fillet dry and cut into medallions 1-2 cm thick. Season with salt and pepper.
Heat 2 tablespoons of oil in a coated pan. Fry medallions vigorously on each side for approx. 1 minute. Place them side by side in a greased ovenproof dish. Heat 1 tablespoon of oil in the frying fat. Fry the mushrooms in it for about 5 minutes. Season with salt and pepper, spread over the medallions. Heat 2 tablespoon butter in the frying fat. Sweat 2 tablespoons of flour in it. Stir in 150 ml of water, milk, cream and stock. Bring to the boil and simmer for 10-15 minutes. Stir in herbs except for something to sprinkle. Season to taste with wine, lemon juice, salt, pepper, nutmeg and a pinch of sugar.
Cut the camembert into thin slices. Spread over the meat and mushrooms. Bake in the preheated oven (electric stove: 200 degrees, convection: 175 degrees, gas: level 2) for 25-30 minutes. Sprinkle with the remaining herbs.
This goes well with mashed potatoes or pasta and a mixed salad.