Peel, wash and halve the potatoes. Cook in salted water for about 20 minutes
Peel and finely dice the onions and garlic. Clean, wash and halve the mushrooms according to size. Peel, wash and chop the carrots. Wash herbs, chop finely
Fry the mushrooms in hot oil while turning. Add onions, garlic and carrots. Fry for another 3-4 minutes. Stir in 3/4 of the thyme and half of the parsley. Season with salt and pepper
Heat milk and fat. Drain and mash the potatoes. Pour in the milk. Season to taste
Pour the mashed potatoes into a greased casserole dish. Put mushrooms in the middle. Mix crème fraîche, rest of parsley and parmesan, season. Spread on the mushrooms. Bake in a hot oven (electric cooker: 200 °C/ convection oven: 175 °C / gas: level 3) for 20-25 minutes. Garnish with rest of thyme