01 - Preheat oven to 400°F.
02 - Pat chicken breasts dry. Using a sharp knife, cut a deep pocket into the side of each breast, being careful not to cut all the way through.
03 - Season chicken breasts inside and out with salt, pepper, and garlic powder.
04 - Stuff each pocket with mozzarella slices, tomato slices, and 4 basil leaves. Secure with toothpicks if needed.
05 - Heat olive oil in an oven-safe skillet over medium-high heat. Sear chicken breasts for 2-3 minutes per side, until golden.
06 - Transfer skillet to preheated oven and bake for 15–18 minutes, or until chicken is cooked through and cheese is melted.
07 - In a small saucepan, combine balsamic vinegar and honey. Bring to a boil, then simmer over low heat for 6–8 minutes, stirring occasionally, until reduced by half and syrupy.
08 - Remove chicken from oven, let rest for 2 minutes, then drizzle with balsamic glaze before serving.