Preheat oven to 400°F (200°C). Pat chicken dry and cut a pocket into each breast.

Stuff each pocket with mozzarella, cherry tomatoes, and basil; secure with toothpicks if needed.

Rub chicken with olive oil, Italian seasoning, salt, and pepper.

Sear in a hot oven-safe skillet 2–3 minutes per side until golden.

Transfer skillet to oven and bake 15–18 minutes, until internal temperature reaches 165°F.

Drizzle with balsamic glaze before serving, if desired.