In the vegetable stock, cook the diced carrots and potatoes for about 10 minutes on medium heat until soft. Add the pre-cooked and peeled chestnuts and cinnamon and simmer on a low flame for another 10 minutes.
Sear the chopped onion and the chopped bacon for about 5 minutes. The onion is allowed to turn brown and crispy. Transfer to a container and set aside.
Immediately fry the finely chopped mushrooms in the same pan with a little butter for about 10 minutes over medium heat, stirring frequently, and then let them simmer on the switched off plate.
Remove half the cinnamon stick from the broth. Add the mushrooms and the beaker of whipped cream and mix with the hand blender until it becomes a creamy mixture. Season to taste with salt and pepper.
Pour a little of the fried onion and bacon mix into a soup cup or soup plate, carefully pour the soup over it and serve immediately with whipped icing or a teaspoon of sour cream and sprinkled with freshly chopped parsley.