1. Sauté chopped carrot, onion, celery and fresh mushrooms in a in 2 tablespoons of butter in a large pot for 5 minutes or until the onions are transparent.
2. In another large pot, melt 1/2 cup butter and stir in the flour.
3. Cook for 5 minutes.
4. Whisk in the chicken broth to the flour mixture.
5. Add the sautéed vegetables, artichokes hearts, bay leaf, salt, cayenne pepper, thyme, oregano and sage.
6. Over medium heat Simmer for 30 minutes.
7. Whisk in cream and add oysters.
8. Bring to a simmer but do not boil.
Personally if I was going to change up this recipe for the better I would use oyster mushrooms instead of button mushrooms to enhance the flavor of the soup. They are a little more expensive but maybe you could just do it for special occasions.
If you really want to kick it up a notch I would exchange out the dried herbs for 3/4 of a teaspoon of fresh herbs of each. Then it would really taste like you went all out.