Bring a large pot of salted water to a boil and add the pasta. While that's happening, heat a skillet over medium heat and add the olive oil and pancetta/bacon (if using). Allow the pancetta to crisp up, and then add the onion and garlic. Cook for about 10 minutes, or until caramelized.
Stir in the orange juice and tomato paste, and bring to a simmer. Season with salt and pepper to taste, and add the half and half. Scoop in your cooked pasta (reserve the cooking liquid), and parmesan cheese. Give everything a good stir. Add in a little more of the starchy pasta water if the sauce needs thinning out.
Stir in the orange zest and basil. Give the pasta a taste and adjust the seasoning if needed. Serve!