01 - Set the oven to 400°F to warm while preparing the other components.
02 - Carefully cut a pocket into the side of each chicken breast without slicing completely through.
03 - Drizzle olive oil over both sides of the chicken breasts, then evenly season with salt, pepper, and Italian seasoning.
04 - Fill each pocket with 2 to 3 slices of mozzarella, several tomato slices, and 4 basil leaves. Use toothpicks if necessary to secure the opening.
05 - Heat an oven-safe skillet over medium-high heat and sear the stuffed breasts for 2 to 3 minutes per side until golden brown.
06 - Transfer the skillet to the oven and bake for 18 to 22 minutes until thoroughly cooked and the cheese has melted.
07 - Combine balsamic vinegar and honey in a small saucepan, simmer over medium heat, stirring occasionally until reduced by half and syrupy, about 8 to 10 minutes.
08 - Remove toothpicks from the chicken, drizzle with balsamic glaze, and serve immediately.