Drizzle a little extra virgin olive oil into a large frying pan and heat over medium heat. Fry the pancetta until golden and crisp, then transfer to a plate lined with kitchen paper to drain.
Leave about a tablespoon of the rendered fat in the pan, then add the finely chopped onion. Cook over medium-low heat for 5-7 minutes, or until translucent.
Add the minced garlic and cook for another minute. Stir in the crushed tomatoes, a splash of white wine (optional), the stock (chicken or vegetable) and a pinch of dried oregano. Season with salt and freshly ground black pepper, then reduce the heat to low and simmer gently for 15-20 minutes.
Meanwhile, bring a large saucepan of salted water to the boil. Cook the rigatoni according to the packet instructions until al dente, about 10-12 minutes. Drain well.
Return the sauce to a gentle heat, add the drained rigatoni and the crispy pancetta, then toss gently to combine. Serve immediately with grated Parmesan or Grana Padano.