Amatriciana is a minimalist equation of pasta, tomatoes, guanciale and pecorino Romano cheese, and in Rome it’s served with barely any sauce, as we learned from Mario Ive, retired artillery colonel in the Italian army and cookbook author. The cooking method—using as little liquid as possible when cooking the sauce—concentrates flavors in the sauce, which coats the pasta nicely. We apply that principle for the pasta in this recipe, as well, cooking spaghetti in half the amount of water (2 quarts) we usually use. To that we add a chunk of pecorino Romano, which infuses the noodles with rich, savory flavor. We also undercook the pasta, allowing it to finish cooking in the sauce. One 14½-ounce can of whole tomatoes, drained and cooked down, is plenty to dress four servings. Likewise, just 3 ounces of pancetta—more widely available than guanciale—provides ample flavor. Be sure to purchase thinly sliced pancetta and chop it finely to ensure the pieces crisp well.