A basic mushroom soup recipe is available in the book "Modern French Cooking for the American Kitchen" by Wolfgang Puck and on FoodNetwork.com. The recipe takes about 55 minutes to prepare and calls for ingredients such as white mushrooms, lemon, shallots, chicken stock and heavy cream.
Take 1 pound of cleaned, firm white mushrooms and sprinkle with the juice from 1 medium lemon. Coarsely chop them in a food processor. Melt 1 tablespoon of unsalted butter in a heavy saucepan, and in it sauté 2 tablespoons of minced shallots. Add the chopped mushrooms along with 1/4 teaspoon of dried thyme and 1/2 of a bay leaf to the butter and shallot mixture, and sauté for about 10 minutes over medium heat until the liquid disappears. Add 1 teaspoon of salt, 1/2 teaspoon of freshly ground pepper, 2 cups of heavy cream and 1 1/2 cups of chicken stock to the saucepan to the saucepan, and bring to a boil, reducing the heat before simmering for 20 minutes.
Dissolve 1 teaspoon of cornstarch into 1 tablespoon of water and stir into the soup. Continue simmering for 10 more minutes while stirring. Taste and adjust seasonings as necessary. To serve, ladle the soup into warm bowls and sprinkle with a touch of minced parsley.