1. In a skillet over medium heat, cook the ground beef with diced onion until the meat is browned and the onion is soft. Drain excess grease and season with salt, pepper, and garlic powder.

2. Wash and thinly slice the potatoes. Try to keep slices even for uniform cooking.

3. In a bowl, mix together the cream of mushroom soup and milk until smooth.

4. Grease a 9×13-inch baking dish with butter or oil. Layer half the potato slices at the bottom.

5. Spread half of the beef mixture over the potatoes, followed by a drizzle of the soup mixture and a sprinkle of cheese.

6. Repeat the layers with remaining potatoes, beef, soup mixture, and cheese.

7. Cover the dish with foil and bake at 375°F (190°C) for 50 minutes.

8. Remove foil and bake for another 15–20 minutes until the top is golden and bubbly.

9. Let rest for 5 minutes before serving.