01 - Bring a large pot of generously salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Reserve 1/2 cup of the starchy cooking water, then drain the pasta in 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 fragrant and translucent, about 3 to 4 minutes.
03 - Pour in the crushed tomatoes, sugar, dried oregano, red pepper flakes, salt, and pepper. Stir to combine and simmer uncovered for 10 to 15 minutes, stirring occasionally, until the sauce thickens and coats the back of a spoon.
04 - Transfer the drained pasta into the skillet with the sauce. Toss thoroughly to coat every strand or piece, adding splashes of the reserved pasta water as needed to achieve a silky, clinging consistency.
05 - Remove the skillet from heat. Fold in the torn basil leaves and grated Parmesan cheese, then drizzle with the remaining tablespoon of olive oil. Toss once more to distribute evenly.
06 - Divide among warm bowls immediately. Garnish with additional Parmesan and fresh basil leaves if desired. Serve alongside a crisp Italian white wine or Chianti for a complete meal.