In a large saucepan, melt the butter over medium-high heat. Add the onions, celery, and shallots, and cook, stirring, until soft, 3 minutes. Add the garlic and cook, stirring, for 30 seconds. Add the mushrooms and thyme, and cook, stirring, until the mushrooms are soft and give up their liquid but are not browned, 4 to 5 minutes. Add the wine and bring to a simmer. Cook, stirring, until reduced by half. Add the cream and oyster liquor and cook, stirring, until slightly thickened. Add the lemon juice and oysters and cook until the oysters begin to curl, 2 to 3 minutes. Stir in the parsley and adjust the seasoning to taste.
Ladle into cream soup bowls and garnish with chopped chives and garlic toast. Serve hot.
Yield: 6 servings