Heat the chicken stock to a simmer in a saucepan
Melt 1½ tablespoons of olive oil in a large skillet with high sides over medium heat. Sauté until the mushrooms are brown and the liquid evaporates. 8-10 minutes. Remove, set aside and chop when cooler.
In the same skillet the remaining olive oil. Cook the onions for 5 to 7 minutes or until translucent. Add the garlic and sauté for 30 seconds more. Add the rice and coat it in the oil, let it cook for about a minute.
Add the wine and allow it to reduce for about a minute as well. Add a ladle full of the simmering chicken stock to the rice, stir constantly and continue to add the stock one ladle at a time making sure to wait until the rice has soaked it all up before adding in another.
When the rice is just about fully cooked, add in one more ladle full of chicken stock and season with salt and pepper. Add in the Mushrooms, Parsley, Parmesan Reggiano and butter, turn the heat off and place a lid on the pan. Let it sit for 5minutes covered.