Preheat oven to 400℉.
Slice pockets into the chicken by making a horizontal cut into the side, not going all the way through.
Season chicken breasts inside and out with salt, pepper and garlic powder. Stuff each chicken breast with 3-4 apple slices and 1 oz of brie cheese. Use toothpicks to hold the chicken together if necessary.
In a large, oven safe skillet over medium high heat, add the oil. Once the pan is hot add in the chicken and brown each side undisturbed, about 2-4 minutes per side.
While chicken is browning, whisk together the maple syrup, dijon mustard, thyme and garlic until smooth. Set aside 2 tablespoons of the mixture in a separate bowl for glazing after the chicken is cooked.
When chicken is browned, brush each breast with the remaining glaze. Place the skillet in the oven and bake until the thickest part of the chicken has reached 165℉, about 20-25 minutes. Brush cooked chicken breasts with reserved glaze.
Let chicken rest for 5 minutes and serve with freshly steamed green beans.