Preparation Toast peppercorns in a dry small skillet over moderately high heat, swirling skillet, until fragrant and peppercorns begin to jump, 2 to 3 minutes. Coarsely crush peppercorns with a mortar and pestle or wrap in a kitchen towel and press on peppercorns with bottom of a heavy skillet. Cook spaghetti in a 6- to 8-quart pot of boiling salted water until al dente. Fill a large glass or ceramic bowl with some hot water to warm bowl. Just before spaghetti is finished cooking, drain bowl but do not dry. Reserve 1/2 cup pasta cooking water, then drain pasta quickly in a colander (do not shake off excess water) and add to warm pasta bowl. Sprinkle 3/4 cup cheese and 3 tablespoons cooking water evenly over spaghetti and toss quickly. If pasta seems dry, toss with some additional cooking water. Divide pasta among 4 plates, then sprinkle with pepper and 2 tablespoons cheese (total). Serve immediately with additional cheese on the side.