Steps
1. Heat the olive oil and butter in a saucepan over medium heat.
2. Add the sliced onions and cook slowly until they are caramelized, about 10-15 minutes.
3. Stir in the sliced mushrooms and cook for another 5 minutes until they soften.
4. Add the Arborio rice to the pan, stirring until the rice is coated with the oil and butter.
5. Gradually add the vegetable broth, one ladle at a time, stirring continuously until the liquid is absorbed before adding more.
6. Continue this process until the rice is creamy and cooked al dente, about 18-20 minutes.
7. Stir in the grated Parmesan cheese, and season with salt and pepper to taste.
8. Serve hot, garnished with fresh parsley if desired.