Season the chicken breasts with salt and pepper.
In a large skillet, heat the olive oil over medium-high heat. Add the chicken breasts and cook until browned on both sides, about 5 minutes per side. Remove the chicken from the skillet and set aside.
In the same skillet, add the chopped onion and garlic. Cook until softened, about 3 minutes.
Stir in the diced tomatoes, chicken broth, oregano, and basil. Bring the mixture to a simmer.
Return the chicken breasts to the skillet, spooning some of the tomato mixture over the top.
Cover the skillet and simmer for 15-20 minutes, or until the chicken is cooked.
Serve the Chicken Napoli hot, garnished with grated Parmesan cheese and fresh basil leaves.