Divide the cauliflower into small florets and wash. Pour off the corn and mushrooms and set them up (I still rinse them with water).
Heat the butter in a saucepan and stir quickly together with the flour. Then deglaze with the vegetable stock. Stir the cauliflower florets, corn and mushrooms into the soup. Season to taste with Maggi, salt, pepper and nutmeg. Then stir in the crème fraiche - do not let it boil anymore.