Heat 3 tablespoons of the olive oil in a sauté pan with the rosemary and garlic. Add the mushrooms, salt, and pepper; cook 5 minutes. Heat 1/4 cup of the olive oil in another pot, add the onion, and cook 5 minutes. Add the Grano and wine; cook until evaporated. Add the broth, 1 cup at a time, adding the next cup only when the previous one has been almost absorbed. After you have added 3 cups, add the mushrooms along with any pan juices. Cook, stirring and adding broth, until the Grano is done; it should take 30-35 minutes. The Grano will be firm and chewy. Fold in the butter, Parmigiano, and the remaining olive oil, and serve.