01 - Cook the pasta in a large pot of salted boiling water according to package directions until al dente. Reserve 1/2 cup of the pasta water; drain the rest.
02 - Heat olive oil in a large skillet over medium heat. Add the onion and sauté for 3-4 minutes until softened. Add garlic and cook for 1 minute more.
03 - Pour in the crushed tomatoes, salt, pepper, and sugar (if using). Simmer for 10 minutes, stirring occasionally.
04 - Reduce heat to low. Stir in the heavy cream and Parmesan cheese. Simmer for 2-3 minutes until the sauce is creamy and slightly thickened.
05 - Add cooked pasta to the sauce, tossing to coat. If needed, use reserved pasta water to reach the desired consistency.
06 - Remove from heat and fold in the fresh basil leaves.
07 - Serve immediately, topped with extra Parmesan and fresh basil.