Heat a cast iron skillet in a 400F degree oven for 20 minutes. **If you're in a hurry, you can skip this and just heat the skillet on high heat for 3-5 minutes.
Season the pork chops with the salt and pepper.
Remove the skillet from the oven and place on the stove over medium-high heat.
Add 1 tablespoon of the butter. Add the pork chops and sear for 3 minutes on each side. Don't touch the pork chops while they're cooking - you want a nice crust to form.
When done, remove the pork chops from the skillet and turn the heat down to medium low.
Add the remaining butter, mushrooms, onions and garlic. Cook for about 3-5 minutes, until the mushrooms have released most of their liquid. Be sure to stir continuously while cooking so the onions and garlic don't burn.
Add the sherry and cook for 30 seconds.
Add the cream, salt and pepper and stir to combine.
Place the pork chops on top of the mushroom gravy and place in the oven for 7-9 minutes, or until the internal temperature reaches 135F degrees. **Cooking time will depend on the thickness of the pork chop.
Remove the pan from the oven and let rest for 10 minutes before serving. Serve pork chops whole or slice them to serve.