Using a sharp knife, cut a pocket into each chicken breast, being careful not to cut all the way through.
Fill each pocket with 2 tablespoons of pesto and 2 slices of mozzarella cheese.
Secure the opening of the chicken pockets with toothpicks to keep the filling inside.
In a large ovenproof skillet, heat the olive oil over medium-high heat.
Season the stuffed chicken breasts with garlic powder, salt, and pepper.
Once the oil is hot, add the chicken breasts to the skillet and sear for about 3-4 minutes on each side, until golden brown.
Remove the skillet from the heat and arrange the halved cherry tomatoes around the chicken.
Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the chicken is cooked through and the internal temperature reaches 165°F (75°C).
Once cooked, remove the skillet from the oven, and let the chicken rest for 5 minutes before removing toothpicks.
Serve the chicken warm, garnished with fresh basil leaves and a drizzle of additional pesto if desired.
Notes
Let the chicken rest before serving for better flavor.