Heat stock in a saucepan over medium heat; reduce to simmer. In cast iron pan over medium heat add olive oil and heat. Add mushrooms and shallots, stirring until translucent. Add rice, stirring until rice begins to make a clicking sound (approximately 3-4 minutes).
Add wine and cook until wine is absorbed. Using a ladle, add 3/4 cup of hot chicken stock to rice, and with a wooden spoon, stir constantly. (Do not stir vigorously or rice will become gluey). When rice is slightly thickened, add another 3/4 cup of stock.
Continue adding stock and constantly stir. As rice nears doneness, add smaller amounts of stock. Rice should not be overcooked, and is done when mixture is consistency of a heavy cream.
Remove from heat and add butter, parmesan, parsley, and season to taste with salt and pepper. Top with additional grated cheese. Serve immediately.