1. Heat a large cast-iron skillet to medium high, adding 1 tablespoon of olive oil. Season both sides of the pork chops with kosher salt and freshly ground black pepper.
2. Add pork chops to skillet, and let them cook undisturbed to get a good sear, about 2-3 minutes, then flip and cook 2-3 minutes on the other side, until chops are cooked through (the time needed will depend upon the thickness of your pork chops). Remove and set aside to a plate; cover to keep hot.
3. In a large bowl, mix apples, onion, and Brussels sprouts, tossing with the rest of the olive oil, 3/4 teaspoon kosher salt, and chopped rosemary. Pour mixture into the skillet and sauté on medium high for 7-9 minutes, until mixture is seared around the edges, and Brussels sprouts are fork-tender.
4. Turn off heat and add pork chops back to skillet, so that each one is surrounded by the Brussels sprout mixture. Sprinkle a little more fresh rosemary over the skillet, and serve!