2. Heat the olive oil over medium heat in a separate, medium-sized pot. Add the onion and cook until it turns translucent, about 5 minutes. Add the mushrooms and cook until they begin to brown around the edges, about 8 minutes. Add the garlic and sage and cook 2 minutes more.
3. Add the rice to the onion mixture, stir and turn the heat to low. Add the white wine and cook until the wine has reduced by half.
4. Add about 1 cup of the hot stock to the rice mixture, and stir slowly until the stock is absorbed. Continue to add the stock 1 cup at a time, stirring slowly, letting the rice absorb the stock before adding more.
5. The risotto is cooked when it is creamy on the outside and slightly firm (al dente) in the center, about 20 to 25 minutes in all. Stir in half of the Parmesan cheese. Season with salt and pepper to taste. If the risotto is too thick, add a little more stock until it becomes creamy.
6. Divide the risotto into serving dishes and sprinkle with the remaining cheese.