Tomato, pork, pecorino, and the hollow noodle built for argument.
Amatriciana is not complicated. This is why people keep complicating it. Pork fat, tomato, pecorino, pasta. That is the room. Stay in it.
Bucatini is ridiculous in the correct way: a noodle with a tunnel, built to carry sauce inside and outside at once. You will splash your shirt. Wear the shirt that forgives.
If you cannot find guanciale, use pancetta and apologize quietly to Rome.
Render pork. Cook guanciale slowly until crisp at the edges and the fat has rendered.
Bloom chili. Add chili flakes to the fat for thirty seconds. Do not let them burn.
Add tomato. Add tomatoes and simmer until thickened and glossy.
Cook pasta. Boil bucatini until shy of done. Save water.
Toss hard. Add pasta to sauce with splashes of water. Toss until the sauce grips.
Finish with cheese. Off heat, add Pecorino and black pepper. Serve with confidence and napkins.
Slow rendering turns pork fat into the cooking medium for the entire sauce.
Tomato reduces in that fat, concentrating sweetness and acidity.
Pasta water and Pecorino bind the sauce so it clings to bucatini instead of sliding away.