Preheat the oven to 400°F.
Heat the olive oil in a large cast iron skillet over medium-high heat. Season the pork chops with salt and pepper on both sides.
Add the pork chops to the hot skillet and sear for about 6 minutes on each side. Transfer the pork chops to a plate and set aside.
While the pork chops are searing, prepare the stuffing according to the package directions. Set aside.
Reduce the heat to medium and melt the butter in the same skillet. Add the sliced onion and cook, stirring occasionally, until soft and golden, about 8 minutes.
Pour the chicken stock into the skillet, scraping the bottom of the pan to loosen any browned bits.
Push the onions to the side and return the pork chops to the skillet. Spoon the onions evenly over the tops of the pork chops.
Divide the apple pie filling evenly among the pork chops, spooning it over the top of each one. Sprinkle with the ground cinnamon.
Divide the prepared stuffing into 4 equal portions and mound one portion on top of each pork chop.
Cover the skillet with a lid and transfer it to the oven. Bake for 20 minutes, then begin checking the internal temperature of the pork chops. Continue baking, covered, as needed until the pork reaches 145°F when an instant-read thermometer is inserted into the thickest part of the chop without touching the bone. **Thicker pork chops may require additional baking time.
Remove the lid and bake for about 5 minutes more to lightly crisp the tops of the stuffing.
Let the pork chops rest for 3 minutes before serving.