Prepare the Broth: In a medium saucepan, bring the vegetable or chicken broth to a simmer over medium heat. Keep it warm on low heat while you prepare the risotto.
Sauté the Vegetables: In a large skillet or heavy-bottomed pot, heat 2 tablespoons of olive oil over medium heat. Add the finely chopped onion and sauté until translucent, about 5 minutes.
Cook the Mushrooms: Add the sliced mushrooms to the pot and continue to sauté until they are browned and softened, about 5-7 minutes. Stir in the minced garlic and cook for an additional minute until fragrant.
Toast the Rice: Add the Arborio rice to the skillet, stirring well to coat it in the oil and to lightly toast for about 2-3 minutes. This step enhances the risotto's flavor and texture.
Deglaze with Wine: If using, pour in the dry white wine and stir until it has mostly evaporated, absorbing into the rice.
Add Broth Gradually: Begin adding the warm broth one ladleful at a time, stirring frequently. Allow the rice to absorb the liquid before adding the next ladle. Continue this process for about 18-20 minutes, until the rice is creamy and cooked al dente.
Finish with Butter and Sage: Once the risotto is cooked, remove it from heat. Stir in 4 tablespoons of unsalted butter, the finely chopped sage, and the grated Parmesan cheese. Season to taste with salt and black pepper.
Serve: Spoon the creamy risotto into bowls and garnish with a sprinkle of fresh parsley and additional Parmesan cheese if desired. Drizzle with a touch of olive oil for an extra burst of flavor.