Clean and wash the beans. In the meantime clean, clean and chop the mushrooms very finely. Peel onion and chop very finely. Crumble the bread very finely. Wash parsley, shake dry and chop finely.
Cover and chill half of the parsley.
For the crust, heat 1 tablespoon of oil in a small pan, add mushrooms and fry vigorously while turning. Add the onion and breadcrumbs and fry briefly. Season well with salt and pepper.
Add half of the parsley. Remove from the pan.
Peel the potatoes, wash them thoroughly and cook in boiling salted water for about 25 minutes. Heat 2 tablespoons of oil in a frying pan, fry the meat in it for about 2 minutes on each side, season with salt and pepper, remove.
Place on a baking tray lined with baking paper. Spread mushroom bread crust evenly on the medallions. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 12-15 minutes.
Put the pan with the frying set aside.
Meanwhile cook the beans in boiling salted water for 12-15 minutes. Peel and finely dice the shallots. Heat 10 g butter in a pan, sauté shallots in it, drain beans, add, heat briefly, keep warm.
Put the roasting set back on a hotplate, heat it up, deglaze with stock and cream, bring to the boil, season with salt and pepper. Simmer for 2-3 minutes, stir in sauce thickener, bring to the boil and simmer for about 1 minute.
Heat milk and 40 g butter. Drain the potatoes, mash them with a potato masher and let the milk-butter mixture run in. Season to taste with nutmeg. Take the baking tray out of the oven.
Arrange meat with sauce, beans and mashed potatoes on plates. Sprinkle with parsley set aside.