Steps
1. In a saucepan, heat the vegetable broth and keep it warm on low heat.
2. In a separate pan, sauté the onions and garlic in olive oil and butter until translucent.
3. Add the Arborio rice to the pan and stir until the rice is coated with the oil.
4. Gradually add the warm vegetable broth, a ladle at a time, stirring constantly until the rice absorbs the liquid.
5. Stir in the sliced mushrooms and continue to add the broth until the rice is creamy and cooked through.
6. Remove from heat and stir in the Parmesan cheese. Season with salt and pepper.
7. Serve hot and garnish with fresh herbs if desired.