2 tablespoons olive oil
1 pound Italian sweet sausage, casings removed, crumbled into 1/2-inch pieces
8 ounces portobello mushrooms, stemmed, dark gills scraped out, caps diced
10 ounces fresh shiitake mushrooms, stemmed, diced
1 teaspoon chopped fresh thyme
1 teaspoon chopped fresh oregano
1 1/2 cups Madeira
6 cups chicken stock or canned low-salt chicken broth
1/2 cup (1 stick) butter
1 large onion, chopped
4 garlic cloves, minced
2 cups arborio rice or other medium-grain rice (about 13 ounces)
1 cup freshly grated Asiago cheese*