In a medium bowl, whisk together balsamic vinegar, honey, olive oil, minced garlic, Italian seasoning, Dijon mustard, salt, and pepper until well combined. Set aside.

Halve the grape tomatoes and place them in a mixing bowl. Add the fresh mozzarella balls and chopped basil, then season with salt and pepper. Toss gently to combine.

Heat 1-2 tablespoons of olive oil in a large oven-safe skillet over medium-high heat. Season the chicken breasts with salt and pepper, then sear them for 1-2 minutes on each side until golden brown.

Once the chicken is seared, pour the prepared balsamic sauce into the skillet. Spread the tomato and mozzarella mixture over the chicken evenly.

Preheat your oven to 400°F (200°C) and then transfer the skillet to the oven. Bake for 18-23 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).

Remove the skillet from the oven and let the chicken rest for about 5 minutes before serving. Garnish with fresh basil if desired.