1. Heat the oil in a large pot over medium heat and sauté the onion until very soft. Add the garlic and cook a few seconds, then add the mushrooms and a healthy pinch of salt. Cook the mushrooms for 3 - 5 minutes until just starting to soften. Remove ¾ of the porcini from the pot and set aside on a plate.
2. Stir in the rice until well coated with the oil.
3. Pour in the wine and cook until evaporated, then ladle in the hot broth about 4 - 6 ounces at a time, stirring constantly. Wait until each addition of broth is absorbed before adding more. Keep adding broth and constantly stirring. The rice will give off its starch and become creamy. At about the 15 minute mark, add the reserved porcini into the rice and continue to cook another 3 - 5 minutes, always stirring until the rice is cooked, but a little resistant to the bite.
Remove the pot from the stove and vigorously stir in the Italian parsley, Parmigiano and butter. Season with salt and pepper. Serve immediately with additional Parmigiano Reggiano.
