Steps
1. In a saucepan, heat the vegetable broth and keep it warm on low heat.
2. In a separate pan, melt the butter and olive oil over medium heat.
3. Add the chopped onion and sauté until translucent, about 3 minutes.
4. Stir in the minced garlic and sliced mushrooms, cooking until the mushrooms are soft, about 5 minutes.
5. Add the arborio rice to the pan and toast it for 1-2 minutes, stirring constantly.
6. Begin adding the warm vegetable broth, one ladle at a time, stirring frequently until the liquid is nearly absorbed before adding more.
7. Continue this process for about 18-20 minutes or until the rice is creamy and al dente.
8. Season with salt and pepper, and stir in the Parmesan cheese if using.
9. Serve hot, garnished with fresh parsley.