• 3 ounces butter, unsalted
• 2 each large celery root, peeled and diced
• 1 leek, white part only, diced and washed
• 1 quart light chicken stock
• ¼ cup Parmigiano-Reggiano, freshly grated
• 1 ounce black truffles, microplane grated
• Kosher salt

Place a heavy bottom soup pot over low heat and add 2 ounces of the butter. When the butter begins to foam, add celery root and a little salt. Cook slowly for 4 minutes, add leeks and continue to cook slowly for another 4 minutes, stirring frequently. Do not allow the celery root or the leeks to brown.

Add chicken stock and bring to a simmer. Cover and cook slowly for 40 minutes.

Carefully puree the soup in a blender until very smooth. Add the remaining 1 ounce of cold butter, all the parmesan and continue to puree until very smooth. Season to taste.

Return soup to a clean pot and heat. Add truffles and serve into warmed soup bowls.