Bucatini all’Amatriciana

I regularly catch Lidia's Italy on TLN, Lidia  was talked about the Lazio Region of Italy, and she proceeded to make Bucantini All'Amatriciana based upon a dish from Amatrice. Originally Lidia used Guanciale, which is hard for me to find so I used pancetta, so here is my rendition of her dish:

Extra Virgin Olive Oil
2 Medium Onions, Quartered and thinly sliced
6 Cloves Garlic, sliced
1 28oz Can Plum Tomatoes passed through a food mill, (preferably San Marzano)
1/4lb Pancetta, 1/4" slices chopped.
1/2 tsp Peperoncino ( more or less to taste)
1/4 cup grated Pecorino Romano
1/4 cup Flat Leaf Parsley Chopped
1lb of Bucantini or Perciatelli
Salt and Black Pepper to taste

I used a technique I saw on the program, put the sliced onions in a hot pan, with some water (I added a 1/4 cup of water + 1/2 cup white wine), to steam the onions and cook them without colouring them.  Once the water has evaporated, move the onions to one side of your skillet and add a couple tablespoons of extra virgin olive oil, add the garlic and peperoncino.  Once the garlic has some colour, mix it with the onions and clear a space for the pancetta.  Once the pancetta is rendered add the milled tomatoes with the liquid from the can, reduce the pan to a simmer.  As a side I add a couple teaspoons of the parsley stems finely minced for extra flavour while the sauce simmers.  Taste for seasoning, adjust pepper and possibly peperoncino to taste.