Preheat the Oven: Preheat your oven to 375°F (190°C). Grease a large casserole dish and set aside.

Cook the Beef Mixture: In a skillet over medium heat, cook the ground beef and diced onion until the beef is browned and fully cooked. Drain excess grease if necessary. Season with garlic powder, salt, and freshly ground black pepper. Set aside.

Prepare the Creamy Sauce: In a mixing bowl, whisk together the condensed cheddar soup, evaporated milk, and regular milk until smooth. Adjust seasoning with salt and pepper to taste.

Layer the Casserole: Spread half of the sliced potatoes evenly in the bottom of the prepared casserole dish. Layer half of the cooked beef mixture over the potatoes. Pour half of the creamy sauce over the beef and sprinkle with 1 cup of grated cheddar cheese. Repeat with the remaining potatoes, beef mixture, creamy sauce, and top with the remaining cheese.

Bake: Cover the casserole with aluminum foil and bake for 45 minutes. Remove the foil and continue baking for another 15-20 minutes, or until the potatoes are tender and the cheese is golden and bubbly.

Serve: Let the casserole rest for 5-10 minutes before serving. Pair with a fresh salad or steamed vegetables for a balanced meal.