Cook the Pasta: Bring a large pot of salted water to a boil and cook pasta until al dente. Reserve 1/2 cup pasta water, then drain.
Sauté the Aromatics: In a large skillet, heat olive oil over medium heat. Add chopped onion and cook for 3–4 minutes until softened. Add garlic and cook for 30 seconds until fragrant.
Simmer the Sauce: Add crushed tomatoes, sugar, salt, pepper, and red pepper flakes. Stir and simmer uncovered for 8–10 minutes until slightly thickened.
Add Cream and Cheese: Lower heat and stir in heavy cream and Parmesan until smooth and creamy. Add a splash of pasta water if needed to loosen the sauce.
Combine with Pasta: Add drained pasta to the skillet and toss for 1–2 minutes until evenly coated and heated through.
Serve: Plate the pasta, top with extra Parmesan and fresh herbs, and serve warm.