Step 1 — Boil the pasta
Bring a large pot of salted water to a boil. Add bucatini and cook until al dente — about 1–2 minutes shy of the package directions. Reserve one cup of pasta water before draining.

Step 2 — Crisp the guanciale
Heat olive oil in a large skillet over medium heat. Add the diced guanciale and cook until the fat renders and the edges turn crisp and golden, about 5–7 minutes. Do not drain that beautiful fat — it’s pure flavor.

Step 3 — Build the sauce
Add red pepper flakes to the pan and stir briefly. Pour in crushed tomatoes and simmer gently for about 10 minutes, until the sauce thickens slightly and deepens in flavor.

Step 4 — Combine pasta and sauce
Add the cooked bucatini directly into the pan with the sauce. Toss to coat, adding small splashes of the reserved pasta water until the sauce becomes glossy and clings perfectly.

Step 5 — Finish and serve
Turn off the heat, sprinkle with Pecorino Romano, and season with freshly ground black pepper. Serve immediately — no waiting. Italians would never let this pasta sit around.