Preparation Steps

• In a small saucepan, combine 0.5 cup of the balsamic vinegar and 1 tablespoon of the honey. Gently simmer over medium-low heat, stirring occasionally, until thickened and reduced by a little more than half, about 15 minutes. Remove from the heat and set aside.
• While the balsamic reduces, arrange the chicken on a cutting board and stretch a large sheet of plastic wrap over the top. Lightly pound the chicken breasts into an even 0.5-inch thickness. Discard the plastic, then sprinkle the chicken with 0.75 teaspoon of the salt and 0.25 teaspoon of the pepper, seasoning both sides.
• In a large, heavy-bottomed skillet, heat 1 tablespoon of the oil over medium-high heat. Once the oil is hot but not smoking, add the chicken breasts top-sides down. Let cook undisturbed for 4 minutes, or until lightly browned.
• Flip and cook an additional 3 minutes. Check for doneness. The chicken should reach 165°F at the thickest part. Remove to a plate and cover to keep warm.
• Without wiping out the pan, reduce the skillet heat to medium. Add the remaining 1 tablespoon of oil, swirl to coat the pan, then add the red onion and let cook until slightly softened, about 3 minutes, scraping the browned bits off the bottom of the pan.
• Add the garlic and let cook 30 seconds, just until fragrant.
• Add the tomatoes, thyme, and remaining 1 tablespoon balsamic vinegar, 1 teaspoon honey, 0.5 teaspoon salt, and 0.25 teaspoon pepper. Increase the heat back to medium high and cook until the tomatoes begin to soften, about 2 minutes.
• Return the chicken to the pan, nestling it into the tomatoes, and scatter the mozzarella throughout.
• Cover the pan and remove from the heat. Let stand for 1 to 2 minutes to allow the mozzarella to become soft and melty.
• Uncover, drizzle the balsamic reduction over the top, and sprinkle with the fresh basil. Serve warm.