Clean and wash the mushrooms, twist out the stems and chop them finely. Steam in hot fat for 5 minutes. Season with salt, pepper and nutmeg. Grate some lemon peel. Wash and chop lemon balm.
Peel and chop the garlic. Knead the ground pork, egg, lemon peel, lemon balm, mushroom stalks and garlic. Season with salt and pepper. Fill the mushroom heads with it, press them a little bit and put them into a flat casserole dish.
Stir crème fraîche until smooth and pour over the mushrooms. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 20-25 minutes.