by Mario Batali
BASIC PASTA DOUGH:
Prepare the pasta dough according to the recipe. Roll it out to the thinnest setting on a pasta rolling machine, then cut the resultant sheet into ribbons 1/4-inch wide. Place the ribbons on a sheet tray dusted with semolina and set aside, covered with clean, damp kitchen towels, until ready to cook.
Bring 6 quarts of water to a boil and add 2 tablespoons salt. In a 12 to 14-inch saute pan, heat oil until smoking. Add the onions, garlic and chili flakes and cook until light golden brown and wilted, 3 to 4 minutes. Add the mushrooms and saute over high heat 5 minutes, until golden brown. Season with salt and pepper, to taste.
Drop the tagliatelle into the boiling water and cook 1 minute. Drain the pasta, reserving the cooking liquid, and add to the pan with the mushrooms. Toss over high heat 1 minute to coat the pasta, adding a splash of the cooking water if necessary to keep the sauce from being too "tight". Add prosciutto and toss to mix. Serve immediately in 4 warmed pasta bowls, topped with Parmigiano-Reggiano.