Using a sharp knife, create a pocket in each chicken breast. Be careful not to cut all the way through.
In a medium bowl, combine the diced mozzarella, halved cherry tomatoes, chopped basil, one tablespoon of olive oil, salt, and pepper. Mix until well combined.
Stuff each chicken breast with the mozzarella and tomato mixture, filling them generously.
Secure the openings of the stuffed chicken breasts with toothpicks to prevent the filling from spilling out during cooking.
In a large oven-safe skillet, heat the remaining tablespoon of olive oil over medium-high heat.
Once the oil is hot, add the stuffed chicken breasts and sear for about 3-4 minutes on each side until golden brown.
Sprinkle garlic powder over the chicken and drizzle with balsamic glaze before transferring the skillet to the preheated oven.
Bake for 20-25 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (75°C).
Remove the chicken from the oven, let it rest for a few minutes, and then garnish with fresh basil leaves before serving.
Notes
Serve the stuffed chicken on a bed of arugula or spinach and drizzle a little extra balsamic glaze on top for an elegant touch.