1. Preheat the oven to 350°F (175°C) to ensure even baking.
2. Brown the ground beef in a skillet over medium heat, adding diced onions and seasonings such as salt, pepper, onion powder, garlic powder, and Worcestershire sauce for flavor.
3. Prepare the potatoes by peeling and slicing them thinly using a mandoline slicer for uniform thickness, or chop into cubes if preferred.
4. In a bowl, mix cream of chicken or mushroom soup with milk until smooth, and season the mixture as desired.
5. Grease a 9×13 inch baking dish with butter or non-stick spray to prevent sticking.
6. Begin layering the casserole: first, lay down a layer of potatoes, followed by browned beef and onions, then pour a portion of the soup mixture, and sprinkle cheddar cheese. Repeat until all ingredients are used, ending with cheese on top.
7. Cover the casserole with aluminum foil to lock in moisture and bake in the preheated oven for about 1 hour.
8. Check the potatoes for tenderness by piercing with a fork; if not tender, bake for an additional 10–15 minutes.
9. Remove the foil and bake uncovered for another 15–30 minutes, until the cheese on top is bubbly and golden.
10. Allow the casserole to rest for 5–10 minutes after baking to set, then serve warm with a side salad or vegetables for a balanced meal.