01 - Heat olive oil and 1 tablespoon unsalted butter in a large saucepan over medium heat. Add the finely chopped onion and sauté until translucent, approximately 3 minutes.
02 - Add minced garlic and sliced mushrooms to the pan. Cook until mushrooms are tender and moisture has evaporated, about 6 minutes.
03 - Stir in Arborio rice and cook for 1 to 2 minutes, coating the grains thoroughly while allowing the edges to become slightly translucent.
04 - Pour in the dry white wine, stirring constantly until the liquid is fully absorbed by the rice.
05 - Incorporate the warm vegetable broth one ladle at a time, stirring frequently and allowing each addition to be absorbed before adding more. Continue this process until the rice is creamy and al dente, about 20 minutes.
06 - Mix in grated Parmesan cheese, the remaining 2 tablespoons of unsalted butter, and heavy cream. Season with salt and freshly ground black pepper to taste.
07 - Remove from heat, cover, and allow the risotto to rest for 2 minutes to meld flavors.
08 - Sprinkle chopped fresh parsley over the top and serve immediately.