Steps
1. In a small saucepan, heat the vegetable broth over low heat and keep it warm.
2. In a medium-sized pan, heat olive oil over medium heat. Add the chopped onion and garlic, sauté until translucent.
3. Add the sliced mushrooms to the pan and cook until they are tender.
4. Stir in the Arborio rice and toast it for about 1-2 minutes, stirring constantly.
5. Gradually add the warm vegetable broth, one ladle at a time, stirring frequently until the liquid is absorbed before adding more.
6. After about 15 minutes, when the rice is almost cooked, stir in the chopped spinach.
7. Once the rice is creamy and al dente, remove from heat and stir in Parmesan cheese and butter (if using). Season with salt and pepper to taste.
8. Serve warm, garnished with extra Parmesan if desired.