Wild Mushroom Fricassee Over Polenta

Name: Wild Mushroom Fricassee Over Polenta
Ingredients: 3 cups chicken stock; 1 cup quick cook polenta, found in Italian foods or specialty foods aisles; 2 tablespoons butter; 1 /4 cup grated Romano or Parmigiano; Salt and freshly ground black pepper; 2 tablespoons extra-virgin olive oil, 2 turns of the pan; 1 tablespoon butter; 4 portobello mushroom caps, halved then thinly sliced; 16 fresh shiitake mushrooms, coarsely chopped; Coarse salt and black pepper; 2 tablespoons balsamic vinegar; 1/2 cup beef stock or broth; 2 scallions, thinly sliced on an angle