Trim the chops of excess fat. Sprinkle generously with salt and pepper on both sides. Heat a 14-inch cast-iron skillet (if you have a smaller one, you'll need to work in batches) over high heat, and then swirl in the olive oil. Lay in the pork chops and don't move them for a few minutes, to assure a good golden sear forms. Turn and brown well on the second side for a total of about 10 minutes. Transfer the chops to a warm plate.
Swirl the butter into the pan. Add the onion and apples. Saute until the onion slices are lightly caramelized and the apples have begun to soften, about 8 minutes. Stir in the beer or other liquid. Return chops to the pan.
Cook until the pork is tender, about 15 more minutes (depending on the size of the chops), turning halfway through and covering the chops with the apple mixture. If the apple mixture needs a little thickening, transfer the chops to the warm plate again and simmer the mixture on high for a few minutes to reduce. Serve the chops over rice or mashed potatoes with a large spoonful of the apple-onion mixture over the top.
Variations include replacing the onion with leeks or adding a sliced potato. You can deglaze the pan with beer, white wine, cider, chicken broth, or even water.