Chop mushrooms with lemon juice in food processor. Melt butter in large skillet over medium heat. Add shallot and saute lightly. Add mushrooms, bay leaf and thyme and cook, stirring frequently, until liquid is completely evaporated, about 10 minutes. Blend cream, chicken stock, salt and pepper and bring to boil. Reduce heat and simmer 20 minutes. Add dissolved cornstarch and simmer 10 minutes longer. Adjust seasoning. Ladle into heated bowls and sprinkle with parsley. Makes 4 to 6 servings.