Preheat your oven to 375°F (190°C).
Prepare the stuffing by combining the diced apple, Brie cheese, and fresh thyme in a bowl. Season with salt and pepper.
Make a pocket in each chicken breast by slicing horizontally without cutting all the way through.
Stuff each chicken breast with the apple and Brie mixture, sealing the openings with toothpicks or kitchen twine.
Season the exterior of the stuffed chicken with salt and pepper.
In a large oven-safe skillet, heat olive oil over medium-high heat. Sear the chicken for 4-5 minutes on each side until golden brown.
Pour the chicken broth into the skillet around the chicken. This helps keep the chicken moist while baking.
Transfer the skillet to the preheated oven and bake for 25-30 minutes or until the chicken reaches an internal temperature of 165°F (75°C).
Remove from the oven, let the chicken rest for 5 minutes, then serve.