01 - Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Drain, reserving 1/2 cup of pasta water, and set aside.
02 - Heat olive oil in a large skillet over medium heat. Add finely chopped onion and sauté for 3 to 4 minutes until softened.
03 - Incorporate minced garlic and cook for 30 seconds until fragrant.
04 - Add crushed tomatoes, tomato paste, sugar, oregano, basil, chili flakes (if using), salt, and black pepper. Stir well to combine.
05 - Reduce heat and simmer sauce for 10 to 12 minutes, stirring occasionally, until thickened and flavors meld.
06 - Add cooked pasta to the sauce, tossing to ensure even coating. Add reserved pasta water incrementally if sauce needs loosening.
07 - Plate the pasta and garnish with grated Parmesan cheese and fresh basil leaves before serving.