Dried chili flakes

Guanciale, San Marzano tomatoes, Pecorino Romano. Rome's other great pasta. Use bucatini if you can find it.

Pancetta instead of guanciale. Easier to find, slightly more smoky. Not traditional but honest.

Replace half the guanciale with 'nduja, the spreadable Calabrian pork sausage. The sauce turns orange-red and deeply spicy.