01 - Bring a large pot of salted water to a boil. Add penne pasta and cook according to package directions until al dente. Reserve 1/2 cup pasta water, then drain.
02 - Heat olive oil in a large skillet over medium heat. Add garlic and onion, sauté for 2-3 minutes until fragrant and softened.
03 - Stir in diced tomatoes, tomato paste, oregano, chili flakes, salt, and pepper. Simmer for 5-7 minutes, stirring occasionally, until slightly thickened.
04 - Add drained pasta directly to the skillet with the sauce. Toss to combine, adding reserved pasta water as needed for a silky sauce.
05 - Stir in chopped basil and grated Parmesan cheese. Cook for 1 minute until cheese melts and pasta is evenly coated.
06 - Serve immediately, garnished with extra basil and Parmesan.