Preheat oven to 350 degrees.Melt the butter in a large skillet over medium heat. Season both sides of the pork with salt and pepper and place in the pan. Brown each side.
Peel and slice the apples and place in a greased baking dish. Sprinkle with brown sugar/cinnamon mixture. For four apples use approx. 1/4 cup brown sugar mixed with 1 tsp. cinnamon.
Top apples with browned pork and cover with aluminum foil.
Bake until meat temperature reaches 145-150 degrees. Tenderloin slices take approx. 30 minutes while other cuts of pork may take longer.