01 - Pat the chicken breasts dry and season both sides generously with salt, pepper, dried oregano, and dried basil.
02 - Heat olive oil in a large skillet over medium-high heat. Place the chicken breasts in the skillet and sear for 3 to 4 minutes per side until a golden crust forms. Transfer the chicken to a plate and set aside.
03 - Reduce the heat to medium and add the butter to the same skillet. Sauté the diced onion for about 2 minutes until translucent, then stir in the minced garlic and cook for 30 seconds 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 juices.
05 - Pour in the dry white wine and chicken broth, scraping up any browned bits from the bottom of the skillet. Bring the liquid to a gentle simmer.
06 - Return the seared chicken breasts to the skillet, nestling them into the sauce. Cover with a lid and simmer over low heat for 12 to 15 minutes until the chicken is cooked through and reaches an internal temperature of 165°F.
07 - Scatter the fresh spinach over the chicken and sauce. Cook uncovered for 2 to 3 minutes until the spinach is wilted. Taste the sauce and adjust seasoning with salt, pepper, and chili flakes if desired.
08 - Serve each chicken breast generously topped with the tomato-spinach pan sauce, alongside rice, pasta, or crusty bread.