• In a large dutch oven heat 2 tablespoons of butter over medium heat. Add the leeks, celery, carrots, rosemary and salt. Cook for an additional 7 minutes. Stir occasionally.
• Add 1 additional tablespoon of butter and let melt. Place the mushrooms into the pan and sauté. Pour the wine into the vegetables and and deglaze until the wine reduces by half.
• Pour the beef stock and mushroom broth (if using) into the pan. Then add the parsley stems, potatoes and nutmeg into the soup. Bring to a boil. Cover and cook until the potatoes are soft, about 20 to 30 minutes. Remove the rosemary and parsley stems
• Optional: remove 3 cups of the soup (more potato and mushroom than broth) and puree in a food processor. Pour the pureed soup back into dutch oven with the remaining soup. If pureed potatoes are not desired, skip this step.
• Add the cream and vinegar to the soup. Allow to simmer at a gentle heat for another 20 minutes. Swirl in the remaining tablespoon of butter and then add the cheese. Mix well, top with parsley and serve.

for the Mushroom Broth

• Remove mushroom stalks and place in a small sauce pan on the stove top. Cover with about 1 ½ cups of water, bring to a boil and lower heat to medium. Reduce liquid to ½ cup. Remove stalks from the broth. This will create a broth that will add more mushroom flavor in the soup.