01 - Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Drain, reserving 1/2 cup of the pasta water.
02 - Heat olive oil in a large skillet over medium heat. Add the onion and sauté for 3–4 minutes until translucent. Stir in the garlic and cook for 1 minute until fragrant.
03 - Add the tomato paste and cook for 1 minute, stirring constantly. Pour in the crushed tomatoes, sugar, red pepper flakes (if using), salt, and pepper. Simmer uncovered for 10 minutes, stirring occasionally.
04 - Reduce heat to low and stir in the heavy cream. Simmer for another 2 minutes until the sauce is creamy and heated through.
05 - Add the drained pasta to the skillet. Toss to coat, adding a splash of reserved pasta water if needed to loosen the sauce.
06 - Remove from heat and stir in most of the fresh basil and Parmesan cheese.
07 - Serve immediately, garnished with extra basil and Parmesan.