In a 3-quart non-reactive saucepan heat the tomatoes over medium heat until juicy, about 5 minutes. Pass the tomatoes through a food mill and puree. Set aside Wipe saucepan clean and return to medium heat. Add olive oil and pancetta and cook, stirring for, about 15 minutes or until pncetta is crisp. Remove from pan with slotted spoon and reserve.

Pour off all but about 2 tablespoons of fat from the pan. Add pnions and cook over medium heat until golden, about 5 minutes. Add white wine and reduce by 3/4. Add reserved tomatoes, chili pepper, and red pepper flakes. Simmer gently for 30 minutes, stirring occasionally with a wooden spoon.

Add reserved pancetta, basil, and 3/4 of the Pecorino Romano. Season with salt and pepper. Simmer for an additional 15 minutes, stirring occasionally. (May be prepared ahead up to this point, and frozen for future use.) Bring 1 gallon of water to a boil and add 1 tablespoon of salt. Cook the bucatini until al dente. Drain and toss with the sauce. Pour into a warmed serving bowl and sprinkle with remaining cheese.Garnish with basil sprigs.