How to Make It
In a large skillet, cook the pancetta over moderate heat, stirring occasionally, until golden brown and the fat is rendered, about 12 minutes. Add the onion and cook until softened, about 8 minutes. Stir in the crushed red pepper and tomatoes, season with salt and black pepper and bring to a boil, then simmer over moderately low heat until the tomato sauce is slightly reduced, about 10 minutes.
Meanwhile, in a large pot of salted boiling water, cook the bucatini until al dente.
Drain the bucatini and add it to the skillet. Toss over low heat until coated in the sauce, about 2 minutes. Transfer to bowls, drizzle with olive oil and serve with grated cheese.