01 -
Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish. Peel and slice the potatoes into thin, even rounds, using a mandoline slicer if available.
02 -
In a large skillet over medium heat, brown the ground beef and sauté the chopped onions until the meat is cooked and the onions are soft, about 5-7 minutes. Drain the excess grease. Season with garlic powder, onion powder, salt, and black pepper, and stir well.
03 -
Layer half of the sliced potatoes evenly on the bottom of the prepared baking dish. Spread half of the cooked ground beef mixture over the potatoes. Repeat with the remaining potatoes and beef.
04 -
In a small bowl, mix the cream of mushroom soup with the milk until smooth. Pour this mixture evenly over the casserole, ensuring it seeps into all layers.
05 -
Sprinkle the shredded cheddar cheese over the casserole. Drizzle melted butter over the cheese. Cover with foil and bake for 45 minutes. Remove the foil and bake for another 15 minutes, or until the cheese is bubbly and slightly golden.
06 -
Let the casserole rest for 5-10 minutes before serving to allow it to set. Garnish with paprika if desired, and serve warm.