First, add the extra virgin olive oil and guanciale to a medium skillet and brown over medium-high heat until the fat has rendered.
Using a slotted spoon, remove the crispy guanciale (or pancetta) onto a paper towel-lined plate and set aside.
Add the finely diced onion to the skillet with the rendered fat from the guanciale and saute on medium heat until translucent.
Then, stir in the minced garlic and red pepper flakes until the garlic becomes fragrant (about 30 seconds).
Next, add the tomato paste to the onions and garlic and stir to combine.
Place the whole peeled tomatoes in a blender or food processor and pulse seven times. Add the blended tomatoes, crispy pancetta, salt, and sugar and combine.
Reduce to low heat and allow the tomato sauce to simmer uncovered for 30-40 minutes. The sauce should be thick and no longer come together once you run a wooden spoon along the bottom of the pan. While the sauce simmers, heat a large pot of salted water to a boil. Cook the rigatoni pasta to al dente according to package directions.
Reserve one-half cup of the pasta water and drain the pasta. Add the cooked pasta to the amatriciana sauce and reduce the heat. Add the pecorino romano cheese and ¼ cup of the pasta water at a time if it is too thick. Serve immediately and garnish with more pecorino cheese and freshly chopped parsley or fresh basil if desired.