2. Heat the olive oil over medium heat in a separate medium-sized pot. Add the onion and cook for 2 to 3 minutes, until it turns translucent, about 5 minutes. Add the zucchini and cook until it becomes golden brown, about 10 minutes.
3. Add the rice to the onion mixture, stir and turn the heat to low. Add about 1 cup of the hot stock to the rice mixture, and stir slowly until the stock is absorbed.
4. 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.