Preheat your oven to 400°F. In a mixing bowl, combine the sliced potatoes, melted butter, and salt. Layer this mixture at the base and along the sides of a 13×9 inch baking dish. Bake for 25-30 minutes, or until the potatoes are nearly tender.
As the potatoes bake, brown the ground beef in a skillet over medium heat. Once cooked through, drain any excess fat. Evenly layer the beef and corn over the baked potatoes. In a separate bowl, mix together the cream soup, milk, garlic powder, pepper, onion, and half of the shredded cheese. Pour this mixture over the beef.
Return to the oven and bake, uncovered, for an additional 20 minutes, or until the casserole has heated through and the veggies are tender. For a golden finish, sprinkle the remaining cheese on top and bake for an extra 2-3 minutes. Garnish with minced parsley, if you prefer.