Heat olive oil in a large pan over medium heat. Sauté the onion and garlic until softened, about 3-4 minutes.
Add the mushrooms and cook until golden, about 5 minutes. Remove and set aside.
Add the chicken pieces and cook until lightly browned. Add the rice and stir to coat with oil.
Pour in the white wine and stir until absorbed. Add the hot stock one ladle at a time, stirring frequently and allowing each addition to be absorbed before adding the next.
Continue cooking and stirring for about 18-20 minutes until the rice is creamy and tender. Return the mushrooms to the pan.
Stir in the butter and Parmesan cheese. Season with salt and pepper to taste. Serve immediately with fresh parsley if desired.
