Add the cream of mushroom soup, sliced mushrooms, chicken broth, garlic powder, dried thyme, salt, and black pepper to the slow cooker. Stir to combine.
Place the pork chops on top of the mixture in a single layer.
Cover and cook on low for 6 to 7 hours until the pork is tender.
About 30 minutes before serving, peel and cube the potatoes. Place them in a large pot, cover with water, and bring to a boil. Cook until fork-tender, about 15 minutes.
Drain the potatoes and return them to the pot. Add the milk and butter, then mash until smooth.
Spoon the mashed potatoes onto plates and top with a pork chop and some of the creamy mushroom sauce. Sprinkle with chopped fresh parsley.