How to Make It
Fill a stockpot with 6 quarts of water, cover, and bring to a boil. In a medium stainless steel bowl, beat the eggs with the mascarpone, 1/2 cup Parmigiano, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Set aside.
Add 3 1/2 tablespoons salt to the boiling water and add the fettuccine. Cover partially just until the water returns to a boil, then uncover, stir the pasta, and cook until al dente.
While the fettuccine is cooking, carefully hold the metal bowl just slightly over the boiling water to warm the egg and cheese mixture, stirring occasionally. When the fettuccine is cooked, drain and add it to the bowl; toss well. Serve immediately, passing the extra Parmigiano at the table.