01 - Pat the chicken breasts dry and season both sides generously with salt and freshly ground black pepper.
02 - Heat 2 tbsp olive oil in a large skillet over medium-high heat. Add the chicken breasts and sear for 3–4 minutes per side until golden brown. Remove from the skillet and set aside.
03 - In the same skillet, add 1 tbsp olive oil. Sauté the finely chopped onion for 2–3 minutes until softened. Add the minced garlic and cook for 30 seconds until fragrant.
04 - Pour in the crushed tomatoes and diced fresh tomatoes. Add dried oregano, chili flakes if using, and sugar to balance the acidity. Stir well and let the sauce simmer for 5 minutes.
05 - Return the seared chicken breasts to the skillet, nestling them into the sauce. Cover with a lid and simmer on low heat for 15–20 minutes until the chicken is cooked through and reaches an internal temperature of 165°F.
06 - Stir the torn basil leaves into the sauce and simmer for 2 more minutes. Serve hot, garnished with grated Parmesan cheese and additional fresh basil leaves.