In a large skillet over medium heat, heat 2 tablespoons of olive oil. Add the mushrooms and cook until they are soft and browned, about 5-7 minutes. Remove the mushrooms from the skillet and set aside. In the same skillet, add the remaining tablespoon of olive oil and the onion. Sauté until the onion is translucent, about 5 minutes.
Add the garlic and Arborio rice to the skillet, stirring constantly for about 2 minutes or until the rice starts to slightly toast and become fragrant. If using wine, pour it into the skillet now, stirring continuously until the wine is mostly absorbed by the rice.
Begin adding the warm vegetable broth, one ladle at a time, stirring often. Wait until the liquid is almost fully absorbed before adding the next ladle of broth. Continue this process until the rice is tender yet fi rm to the bite, and the mixture is creamy, which should take about 18-20 minutes.
Stir the cooked mushrooms, Parmesan cheese, and parsley into the risotto. Season with salt and pepper to taste. Serve warm, garnishing with additional Parmesan and parsley if desired.