Preheat the oven to 375°F (190°C).
Cut a pocket into each chicken breast. Season both inside and outside with salt and pepper.
Fill each pocket with brie slices and apple slices, securing with toothpicks if needed.
In an oven-safe skillet, heat olive oil over medium heat. Sear chicken breasts for about 3 minutes per side until golden brown.
In a small bowl, whisk together maple syrup, Dijon mustard, and apple cider vinegar.
Pour the glaze over the chicken breasts, coating them evenly. Transfer the skillet to the oven and bake for 20-25 minutes, until the chicken is fully cooked and glaze is caramelized.
Let the chicken rest for a few minutes. Garnish with fresh thyme sprigs and serve warm.
