TAGLIATELLE WITH WHITE MEAT SAUCE

Steps:

• For the sauce: Put the ground meats in a large bowl; loosen, crumble, and toss the meats together with your fingers.
• Drop the chunks of onion, carrot, and celery into the food processor, and mince fine, to an even-textured paste. Pour the olive oil and drop the butter into the big saucepan, and set over medium-high heat. When the butter has melted, scrape in the paste, or pestata, season with 1 teaspoon of the salt, and cook and stir the pestata until it has dried out and just begins to stick to the bottom of the pan, about 5 minutes.
• Quickly crumble all the meat into the pan, stir with the pestata, sprinkle over it 1 more teaspoon of salt, and cook, tossing and stirring occasionally, until the meat starts to release its juices. Turn up the heat a bit, and continue cooking and stirring the meat as the juices evaporate, about 10 minutes, taking care that the meat doesn't brown or crisp.
• When the juices have disappeared, pour in the white wine, bring it to a bubbling simmer, and cook until evaporated, 2 or 3 minutes. Meanwhile, stir the tomato paste into the milk until blended. When the wine has cooked away, pour in the milk and cook, stirring, until it has cooked down.
• Now ladle 2 cups or more of the hot stock (or water) into the pan, just enough to cover the meat. Stir in the bay leaves and the remaining salt, and bring the liquid to an active simmer. Cover the pan, adjust the heat so the liquid is steadily bubbling (not boiling rapidly), and cook for 15 to 20 minutes, as the broth gradually reduces. Stir in about 2 more cups hot stock, just to cover the meat again, then give another 20-minute period of covered cooking and reducing. Stir in a final addition of 2 cups stock, and cook, covered, until the ragù is thick and concentrated, 20 minutes or so. (The sauce should have cooked for at least an hour and incorporated 6 to 8 cups of stock in total.)
• Taste the ragù and adjust the seasoning. If you've prepared it in advance, let it cool, then refrigerate and freeze as you wish. Or you can remove about half (for future use) and prepare tagliatelle now, keeping about 3 1/2 cups of freshly cooked sauce in the big saucepan, to dress the pasta.
• To cook the tagliatelle: Bring a large pot of well-salted water to the boil. Shake the nests of tagliatelle in a colander or strainer to remove excess flour. Drop all the pasta into the pot at once, and stir to loosen and separate the strands. Cover the pot, and return the water to a boil rapidly. Set the cover ajar, and cook the pasta, stirring occasionally, for 2 minutes or more, until barely al dente (the pasta will cook a bit more in the pan of sauce).
• Meanwhile, heat the ragù to a simmer. If it has cooled (or been chilled or frozen), it will have thickened, so reheat it slowly in a wide pan, stirring in a cup or so of stock or water, to loosen it.
• Lift the al dente tagliatelle from the cooking pot quickly, with a spider and tongs, drain briefly, and drop the pasta into the simmering ragù. Toss together, over low heat, for a minute or more, until all the strands are coated and perfectly cooked. Thin the sauce, if necessary, with hot pasta water, or thicken it quickly over higher heat.
• Turn off the heat, sprinkle a cup or so of grated cheese over the tagliatelle, and toss well. Finish with a drizzle of olive oil, toss again, and heap the pasta in warm bowls. Serve immediately, with more cheese at the table.