6 tablespoons butter
1 celery rib, diced
4 shallots, diced
1 medium onion, diced
4 garlic cloves, minced
6 ounces shiitake mushrooms, chopped
6 ounces crimini mushrooms, chopped
6 ounces oyster mushrooms, chopped
3/4 cup dry white wine (Sauvignon Blanc works well)
1/4 cup dry Sherry
1/4 cup all purpose flour
4-6 cups chicken stock
1 cup evaporated skim milk
1 tablespoon truffle oil
1/4 teaspoon thyme
Melt 3 tablespoons butter in large sauce pot over medium-high heat. Add celery, shallots, onion, garlic and thyme. Turn down to medium. Cook, stirring occasionally about 7 minutes. Add mushrooms and saute 5 minutes. Add wine and sherry. Bring everything to a boil. Cook about 5-7 minutes, stirring often, until liquid is reduced.
Melt remaining 3 tablespoons butter in medium saute pan over medium heat. Add flour and whisk until mixture resembles a golden paste. Add 1 cup chicken stock to paste and whisk in until creamy. Add to sauce pot and stir until paste and vegetables are mixed together. Add remaining chicken stock. (If soup is too thick add all 6 cups stock, if not, just use 4 cups). Bring to boil, stirring frequently. Reduce heat to so that mixture simmers. Cook about 10 minutes.
Puree soup in blender or processor until smooth. Return soup to pot and add milk and truffle oil. Salt and pepper to taste. Bring to simmer and cook additional 5 minutes.