Amatriciana

Italian specialty markets, gourmet delis, or online retailers like Busnelli or Eataly. If you cannot find it, ask the deli counter to order it—it ships well and freezes for up to 6 months.

Pancetta is the closest substitute and will work acceptably, though it lacks guanciale's peppery depth and unique fat profile—the dish will taste less complex. Bacon will make it taste Americanized and smoky. Use guanciale if at all possible.

Guanciale renders fat as it cooks. If the sauce looks oily, spoon off excess fat before adding tomatoes, but preserve the flavor-rich rendered fat. You should see rendered fat, not a pool of it.

Yes. Make the sauce up to 2 days ahead and refrigerate. The fat will solidify slightly—reheat gently over medium-low heat, stirring occasionally, and add a splash of water if needed. Toss with freshly cooked pasta.

Use grated Pecorino Toscano or, if necessary, Parmigiano-Reggiano, though Pecorino's sharper, saltier flavor is more authentic and better suited to the dish.

Refrigerate in an airtight container for up to 2 days. Reheat gently in a skillet over medium-low heat with a splash of water to restore the sauce, and finish tossing with hot pasta so it doesn't clump.