Let's start by bringing a large saucepan of water to boil. For the best texture, use 1 litre of water per 100 g of pasta, and add in a large pinch of good quality rock salt.
1 pinch rock salt
Once the water's boiling, add your pasta and cook for a few minutes LESS than the packet directions indicate (the pasta will continue to cook when it's added into the sauce). Take out 2 cups of the pasta water to use in the sauce then drain the pasta.
400 g pasta, 2 cups pasta water
Meanwhile, heat the olive oil in a large pan over a high heat. Add the onion, chillis and guanciale/pancetta or bacon pieces, and stir fry until gorgeously fragrant.
200 g guanciale, 1 onion, ¼ cup olive oil, 1 small red chilli
The next step is to add the passata and start with 2 ladles of pasta water (not the whole 2 cups!). Stir everything through then reduce heat to low and simmer for a few minutes. Optional: If you decide the sauce is too thick, then you can add more pasta water - we recommend a half a ladle at a time.
400 g passata, 2 cups pasta water
Now for the fun part! Place the drained pasta on top of the sauce, but DON'T mix through yet. First, top the pasta with your grated pecorino romano cheese and gently mix it through the pasta (avoiding the sauce as much as possible).
½ cup pecorino romano cheese
Once the pasta is coated with that wonderfully melted cheese, you can start to slowly mix it in with the sauce. It should bind nicely to the cheese-coated pasta.
To serve, portion out the pasta into serving bowls, leaving some of the cooked pancetta to place on the top as a garnish.