Next to linguine with clams, this is my favorite pasta dish. I will always order it if it is on the menu when I'm in an Italian restaurant. Like so many Italian dishes, the preparation really varies. I've had it slightly creamy, with chopped hard-boiled egg on top and over many different types of pasta. You may substitute your favorite noodle too.
Set a large pot of water over high heat and bring to a boil.2.
Place 1 tablespoon of the olive oil and the pancetta in a large skillet over high heat and cook until the fat is completely rendered and the pancetta is crispy, about 6 to 8 minutes. Pour off the fat and reduce the heat to medium-low. Add the remaining tablespoon of olive oil and 1 tablespoon of the butter. Add the shallots and red pepper flakes and cook, stirring, for 1 minute. Add the tomatoes and bring to a boil. Reduce the heat and simmer, stirring occasionally, for 30 minutes. Swirl in the remaining tablespoon of butter.3.
Meanwhile, generously salt the boiling water. Add the spaghetti and cook until tender but still firm. Set the timer for 2 minutes less than the package instructions specify and taste for doneness. Drain the pasta and add it to the sauce.4.
Toss the cooked pasta with the sauce to coat and serve topped with freshly grated Pecorino Romano cheese.