Italian Sausage And Mushroom Risotto

Name: Italian Sausage And Mushroom Risotto
Ingredients: 2 Tbsp olive oil; 1 pound Italian sweet sausage, removed from casings, crumbled; 1/2 pound portobello mushrooms, stemmed, dark gills scraped out, caps diced; 10 ounces fresh shiitake mushrooms, stemmed, diced; 1 teaspoon chopped fresh oregano; 1 teaspoon chopped fresh thyme; 1 1/2 cups Madeira (divided, 1/2 cup and 1 cup); 6 cups chicken stock (use gluten-free stock if cooking gluten-free); 1/2 cup (1 stick) butter; 1 large onion, chopped; 4 garlic cloves, minced; 2 cups arborio rice; 1/2 cup freshly grated Asiago or Parmesan cheese (for topping)