01 - Pat the chicken breasts dry and season both sides evenly with kosher salt, freshly ground black pepper, dried oregano, and dried basil.
02 - Heat olive oil in a large skillet over medium-high heat. Sear the chicken breasts for 5 to 6 minutes per side until a golden crust forms and the internal temperature reaches 165°F. Transfer to a plate and set aside.
03 - In the same skillet, add the diced onion and sauté for about 3 minutes until softened and translucent. Stir in the minced garlic and cook for 1 additional minute until fragrant.
04 - Add the halved cherry tomatoes to the skillet and cook for 3 to 4 minutes, stirring occasionally, until they begin to soften and release their natural juices. Pour in the chicken broth and bring the mixture to a gentle simmer.
05 - Fold the chopped spinach into the tomato mixture and cook for approximately 2 minutes, stirring gently, until the leaves are just wilted.
06 - Return the seared chicken breasts to the skillet, nestling them into the tomato-spinach mixture. Simmer for 2 to 3 minutes to heat through and allow the flavors to meld.
07 - Transfer to plates and sprinkle with freshly grated Parmesan cheese if desired. Serve immediately.