Place the pancetta, onion, carrot and celery in the bowl of a food processor and process until finely chopped. In a 10-inch skillet, heat the oil over medium heat. Add the vegetable mixture and cook, stirring, for about 5 minutes. Gradually add the wine and tomato paste. Mix well to combine and add the tomatoes, their juices, and the basil leaves, torn. Break up the tomatoes with the back of a spoon and cover, cooking for 30 minutes, stirring occasionally. Season with salt and pepper, to taste.
Meanwhile, bring 6 quarts of water to a boil and add 2 tablespoons salt. Cook the spaghetti according to the directions, until tender yet al dente. Drain the pasta, reserving 1/2 cup of the cooking water. Add the pasta to the pan with the sauce, then add the ricotta and parsley and toss over high heat 30 seconds, adding the cooking water if necessary to keep the condiment from becoming too tight. Season with salt and pepper to taste and divide evenly among 6 warmed pasta bowls.
Recipe copyright 2000, Mario Batali. All Rights Reserved.