For the Jerusalem artichoke mousse, peel Jerusalem artichoke and cut into coarse pieces. Put the Jerusalem artichoke on the side.
Peel and chop the onion and sauté in some of the butter until translucent. Add the Jerusalem artichoke pieces to the onion, deglaze with the white wine and pour in the vegetable soup.
Cook for about 15 minutes (depending on the size). In the meantime, clean the mushrooms and cut them into thin slices.
Also finely slice the Jerusalem artichokes that have been set aside. Roast them together with the remaining butter. Add a little salt.
When the resulting liquid has evaporated, add the chopped garlic and keep warm. Puree the soup and add the whipped cream.
Season to taste and bring to the boil again. Before serving, blend the Jerusalem artichoke soup again and serve with the mushrooms and the Jerusalem artichoke slices as a garnish.