Opting to follow the crowds instead of the guidebooks, my husband and I ended up in a packed working-class lunch spot in Naples a few years ago. After a glance around, we decided to have what everyone else was having: rigatoni in tomato sauce topped with a dollop of snow-white ricotta. Eyeing the other diners, we did what they did, stirring in the fluffy ricotta before diving in. The cheese made the tomato sauce so mellow and creamy. If you’re preparing pasta with tomato sauce in the weeks ahead, please try this technique. If your sauce also has eggplant, zucchini or sweet peppers, so much the better.