Have your butcher cut pockets for stuffing into the chicken breasts.
Preheat the oven to 450 F.
Warm 1 tablespoon butter in a large, non-stick saute pan over medium-high heat. Add the apples and saute until softened. Set the saute pan aside because you will need it again.
Tuck a slice of Brie and several slices of apple into the prepared chicken breast. Season the chicken with salt and pepper and dust in flour.
In the saute pan, warm 1 tablespoon butter over high heat. When the butter foams add the chicken breasts and brown them on both sides. Transfer the chicken to a sheet pan and roast in the oven until to 160 degrees internal (about 12 minutes). Do not overcook!
While the chicken is cooking, make the sauce. Pour the cider and broth into the saute pan and simmer to reduce to taste, about 25-30%. Remove from the heat and swirl in the remaining 2 tablespoons of butter. Season to taste with salt and pepper. Serve the chicken drizzled with a little of the sauce, serving the rest on the side.
