Crisp up the pancetta. In a large braiser or skillet, heat the olive oil over medium-low heat. Add the pancetta to the pan and cook, stirring occasionally, until the pancetta is crispy. Use a slotted spoon to remove the pancetta from the pan and transfer to a small bowl.
Sweat the onions and garlic. Add the butter to the skillet and stir in the minced shallots, garlic, and red pepper flakes. Cook, stirring occasionally, until the shallots are soft and the garlic is fragrant. Stir in the tomato paste and cook for 3-4 minutes until the tomato paste has darkened in color. Add the red wine and use a wooden spoon or silicone spoon to scrape up any browned bits. Bring to a simmer for 5 minutes.
Simmer the sauce. Stir in the crushed tomatoes and pancetta (save some for garnish) with the basil leaves and season the sauce with some salt and pepper. Bring to a gentle simmer for 15 minutes.
Cook the pasta. While the sauce reduces, bring a pot of salted water to a boil. Cook the pasta until just shy of al dente, usually 2-3 minutes shy of the box instructions. Reserve ½ cup of the pasta water, then drain the pasta.
Finish the pasta. Add the cream to the tomato sauce and stir well. Once the cream is incorporated, stir in the pasta water and drained pasta and stir well. Simmer 4-5 minutes until the sauce clings to the pasta. Season to taste with salt and pepper. Spoon the pasta into bowls and top with parmesan, the reserved pancetta, and some more torn basil leaves.