Preheat oven to oven to 225°F Brush the bottom of a heavy Dutch Oven with some of the butter.
Spread half of the potatoes on bottom of pot, top with pork chops. Sprinkle chops with some of the salt and pepper. Layer the onions on top of the chops, sprinkle with more salt and pepper. Cover with remaining potatoes. Make sure top layer of potatoes doesn't touch the lid of the pot.
Pour in the stout, brush potatoes with remaining butter and sprinkle with remaining salt and pepper.
Cover pot and bake for 8 hours. Check every so often to make sure it isn't drying out. Add water, 1/4 cup at a time, if needed.