Cook Fettuccine in a large quantity of lightly salted water. Meanwhile, cut butter into small pieces and place into a large, warm serving bowl. When the pasta is cooked al dente, drain it and reserve 1/4 cup of the cooking water. Add some of the reserved water to the butter, and then add the fettuccine, mixing with the butter. Add the Parmigiano and continue to mix until creamy. Add some fresh black pepper and serve immediately.