Line the insert of a slow cooker with aluminum foil, forming a bowl and leaving enough for an overhang and spray with non-stick spray. Melt 2 tablespoons of the butter and mix with the potatoes, parsley, garlic powder, onion powder, salt, dill, and pepper. Add all ingredients to the aluminum foil lined slow cooker and fold the extra foil over the potatoes to cover. Cook on low for 4 hours. When the potatoes are done, melt the remaining 2 tablespoons of butter and mix with the potatoes. Serve immediately or keep warm until ready to serve.