01 - Bring a large pot of generously salted water to a rolling boil. Add the pasta and cook according to package instructions until al dente. Reserve ½ cup of the starchy cooking water, then drain the pasta through a colander.
02 - While the pasta cooks, warm the olive oil in a large skillet over medium heat. Add the minced garlic and chopped onion, sautéing until the onion turns translucent and the garlic becomes fragrant, about 3 to 4 minutes.
03 - Pour in the crushed tomatoes, sugar, dried oregano, red pepper flakes, and season with salt and pepper. Stir to combine and let the sauce simmer uncovered for 10 to 15 minutes, stirring occasionally, until it thickens and the flavors concentrate.
04 - Transfer the drained pasta directly into the skillet with the sauce. Toss vigorously to coat every strand or piece evenly, adding splashes of the reserved pasta water as needed to reach a silky, glossy consistency.
05 - Remove the skillet from the heat. Scatter in the torn fresh basil and grated Parmesan, tossing gently until the cheese just begins to melt. Drizzle with olive oil for a lustrous finish.
06 - Divide among warm plates or bowls immediately. Offer additional grated Parmesan and whole basil leaves at the table for garnish.