Purée of Portabello Mushroom Soup

Ingredients

 * 2 	tablespoons extra virgin olive oil
 * 1 	tablespoon butter (optional)
 * 1 	cup diced onions
 * 1/2 	cup diced celery
 * 1/2 	cup diced leeks
 * 1 	lb portabello Mushrooms, gills removed, trimmed and diced
 * 1/2 	teaspoon chopped garlic, to taste
 * 1/4 	teaspoon chopped fresh thyme leaves
 * 1/2 	cup dry sherry
 * 6 	cups vegetable stock
 * salt & freshly ground black pepper
 * 1/2 	cup freshly grated Parmesan cheese

Directions

 * 1) In a large saucepan over medium heat, melt together the olive oil and butter, then add the Onion, celery, and leeks, and sauté until translucent, about 5 minutes.
 * 2) Add the cleaned and trimmed sliced portabellos, garlic, and thyme and cook an additional 5 minutes, stirring often.
 * 3) Add the sherry and sauté until the liquid is reduced to about 1 tablespoon, about 5 to 7 minutes.
 * 4) Add the stock and increase temperature to bring to a boil, then reduce heat and simmer for 15 minutes; season to taste with salt and freshly ground pepper.
 * 5) Puree batches of soup in a well-covered blender, processing until smooth and all the soup has been made creamy.
 * 6) Return soup to saucepan and make sure it’s all heated through.
 * 7) Garnish servings with Parmesan cheese, and enjoy