In a large skillet, heat the olive oil over medium heat. Add the onion and garlic and cook until softened.
Add the Arborio rice and cook for another 2 minutes, stirring constantly.
Pour in the white wine and cook until it has evaporated.
Add the chicken broth, one cup at a time, stirring constantly until each cup is absorbed before adding the next.
Stir in the mushrooms and continue to cook until the rice is tender and creamy.
Add the cooked chicken, Parmesan cheese, and butter. Stir until everything is well combined and heated through.
Season with salt and pepper to taste.
Serve hot and enjoy!