Cut the pork into 1 inch thick slices. Place between sheets of waxed paper and pound to 1/4 inch thickness. season with salt and pepper.
In a large skillet over medium heat, melt 2 tbsp of the butter. Add pork slices and cook 2 minutes on each side, or until cooked through. Transfer to a warmed platter and cover with foil to keep warm.
In the same skillet over medium heat, melt the remaining 2 tbsp butter. Add the apples and saute for 2-3 minutes, or until the apples are lightly browned. With a slotted spoon, transfer the apples to the platter with the pork.
In the same skillet ovewr medium heat, add the shallot and cook for a minute. Add the sage, cider, and vinegar and bring to a boil, scraping any browned bits from the bottom of the pan. Add the chicken stock and boil, stirring for 3 to 4 minutes, or until reduced by half. Stir in the cream, pork, and juices from the platter. Cook, turning the pork once, for 1 or 2 minutes.
Serve pork with sauce spooned over the pork and apple on the side. Sprinkle parsley over to garnish.