In a medium saucepan, heat the chicken broth over low heat. Keeping it warm helps the rice absorb the liquid properly.
In a large saucepan, heat the olive oil and one tablespoon of butter over medium heat. Add the finely chopped onion and sauté until translucent, about 3-4 minutes. Stir in the minced garlic and cook for an additional minute until fragrant.
Add the sliced mushrooms to the pan and cook until they are tender and browned, about 5-7 minutes. Season with salt and pepper to taste.
Add the Arborio rice to the pan with the mushrooms. Stir well to coat the rice with the oil and butter, allowing it to toast for about 2 minutes.
Begin adding the warm chicken broth to the rice mixture, one ladleful at a time. Stir constantly and allow the rice to absorb most of the liquid before adding more, for about 18-20 minutes.
Once the rice is cooked to your liking, remove it from the heat and stir in the remaining tablespoon of butter and the grated Parmesan cheese. Mix until well combined and creamy.
Serve the Creamy Mushroom Risotto hot, garnished with chopped fresh parsley for a pop of color and freshness.