To make the glaze:
Whisk your glaze ingredients together and set it aside.
To make the stuffed chicken:
Preheat your oven to 400 degrees.
Then lay your chicken breasts flat on a cutting board and cut a slit into each one about ¾ of the way through. Season both sides with salt and pepper.
Next heat a large cast iron skillet over medium-high heat and add a splash of olive oil to the pan. Once hot, place your chicken breasts in the pan and sear for 2-3 minutes per side. Then remove your chicken from the pan and stuff them with your sliced apples and brie. (At this point you can secure the chicken with toothpicks in case you're nervous about the filling spilling out.)
Return your chicken back to the cast iron and brush them with your glaze.
Then place the cast iron in the oven and bake for 20-22 minutes or until the chicken is cooked all the way through. (The internal temperature should be 165 degrees once they're done.)
Serve immediately!i