In a 4-quart pot, melt butter over medium heat. Add green onions, celery, and garlic and sauté until soft. Drain and cut the artichokes, and add to the mixture. Sprinkle with flour and stir to coat the vegetables. Gradually add the chicken stock, stirring constantly. Add the cayenne, salt, fennel seed and thyme. Cover and simmer for 1 hour. Add the oysters, oyster liquid, and simmer for 10 minutes. Cool and refrigerate for 8 hours.

Before serving, heat the soup slowly over low heat. Makes 1 gallon, serves 8 bowls.