Make sure to have a pot of boiling salted water for pasta going before starting this dish. You will not cook the pasta all the way as you will finish it in the pan with the sauce.
Drop the pasta into the boiling water to start the cooking process.
Meanwhile, in a saute pan heat some oil over high heat and add the pancetta. Saute until the pancetta is rendered (most of the fat melts away), and then turn the heat down to medium. Pancetta should look like crispy bacon. Add the onions and stir constantly making sure the onions do not burn. Once the onions are soft and cooked through, add the red sauce. Cook for 1 minute, and then add the cheese and pepper flakes, stirring to incorporate.
Turn off the heat on the sauce and add the cooked pasta to the pan with the sauce. Turn the heat back on to low and toss the pasta constantly so that the sauce will stick to the pasta (the sauce should be thick and shouldn't create a pool on the plate). Transfer the pasta and sauce to a bowl and sprinkle more cheese on top to serve.
For best results for a red sauce, crush one 28-ounce can of Italian plum tomatoes or San Marzano tomatoes with the back of a fork until they are mashed, but still chunky. You can also use a simple jarred tomato/basil sauce from your grocery store.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.