In a bowl, whisk together the balsamic vinegar, honey, oil, garlic, Italian seasoning, and Dijon mustard. Season with salt and pepper, then set aside.

In another bowl, toss the grape tomatoes, mozzarella, and basil together. Season with salt and pepper, then set aside.

Preheat the oven to 400 degrees F.

Heat avocado oil in a large oven-safe skillet over medium-high heat. Season the chicken with salt and pepper. Once the pan is hot, add the chicken and cook for 1-2 minutes on each side until lightly golden brown.

Add the balsamic sauce mixture to the skillet and bring to a simmer, scraping up any brown bits from the pan.

Remove the skillet from heat and top the chicken with the tomato mozzarella mixture.

Bake uncovered for 18 to 23 minutes until the chicken is fully cooked through with an internal temperature of 165F. Rest for 5 minutes before serving.