One week in Italy, and you think you're ready to execute such trattoria classics as spaghetti carbonara and bucatini amatriciana in your own home? It can be done, but first you'll have to learn to think outside the Ronzoni box. Pasta needs to be fresh (ideally, made that very day), light and tender (from hours of hand-kneading), and, if it's tortellini or ravioli, the filling had better be able to hold its own in a simple butter sauce. A lot of the "fresh" pasta you find in Manhattan shops is tough, thick, and dried-out, having sat too long on counters or in freezers. But at Cassinelli in Astoria, co-owners Nella Costella and Antonio Bonfigli, both from Italy, endlessly work their dough to produce 30 different types of pasta daily. When cooked, their delicate, soft-shelled ravioli and manicotti ooze light and fluffy ricotta. Eat it and weep.