For the mushroom soup, first prepare the roux. To do this, melt the butter in a saucepan, add the flour and roast. Pour in cold soup and let it simmer.
In the meantime, put the butter in a pan and add the mushrooms cut into slices and sauté. Mix in the parsley. Mix the mushrooms into the soup and serve the mushroom soup hot.
Preparation Tip:
Garnish the mushroom soup with chopped chives or toasted brown bread croutons.