Heat two tablespoons of the oil in a large skillet over medium heat. Add half the porcini and garlic, season with salt and pepper and cook over high heat, turning the porcini gently with a spatula, until lightly browned, 2 to 3 minutes. Transfer the porcini to a plate and repeat with the remaining oil, garlic and porcini. Discard the garlic. Return all the porcini to the pan and add the butter and the parsley. Add the stock and simmer over moderate heat for1 minute. Season with salt and pepper to taste. Meanwhile, cook the pappardelle in a large pot of boiling salted water until al dente. Drain well. Add the pappardelle to the porcini and toss gently, adding half the cheese. Serve immediately, with the remaining cheese passed separately.
Makes 4 servings