1. In a large stainless-steel frying pan, cook the bacon over moderate heat until almost crisp. Remove with a slotted spoon. Pour off all but 1 tablespoon of the fat from the pan.
2. Reduce the heat to moderately low. Add the onion and cook, stirring occasionally, until soft, about 5 minutes. Add the tomatoes with their juice, the salt, and the pepper and bring to a simmer. Cover and cook for 10 minutes.
3. In a large pot of boiling, salted water, cook the cavatelli until just done, about 10 minutes. Drain and toss with the sauce, bacon, arugula, and 1/4 cup of the Parmesan. Stir until the arugula just wilts. Sprinkle the remaining Parmesan over the top.
Variations: Use 1 1/4 cups watercress or spinach, large stems removed, instead of the arugula.
Cavatelli Options: Look for cavatelli in the frozen-foods section of your grocery store. If you prefer, substitute frozen egg noodles or gnocchi in equal amounts for the cavatelli; they have a similar doughy chew. This dish could also be made successfully with spaghetti or, even better, spaghettini.
Wine Recommendation: Barbera is unique among Italian reds in that it is fruity and very high in acid, yet has almost no tannins. These qualities make the wine remarkably adaptable to food, particularly tomatoes. Try an unoaked Barbera d'Alba for a delicious match here.