Preheat the oven to 375°F.
Using a sharp knife, carefully cut a pocket into each chicken breast, being careful not to cut all the way through.
In a mixing bowl, combine the diced apple, Brie cheese, and chopped rosemary. Season with salt and pepper.
Stuff each chicken breast with the apple and Brie mixture, securing the opening with toothpicks if necessary.
In a large oven-safe skillet, heat the olive oil over medium-high heat. Season the outside of the chicken breasts with salt, pepper, garlic powder, and onion powder.
Add the chicken breasts to the skillet and sear for about 3-4 minutes on each side until golden brown.
Pour the chicken broth and balsamic vinegar into the skillet around the chicken. Bring to a simmer, then transfer 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.
Remove from the oven and let the chicken rest for 5 minutes before slicing. Serve warm, drizzled with the pan juices.