01 -
Preheat the oven to 350°F (177°C). Spray a 9x13-inch baking dish with nonstick cooking spray. Set aside.
02 -
Place ground beef and diced onion into a large skillet over medium-high heat. Season with salt and pepper. Cook until the beef is thoroughly browned and no longer pink, breaking up the meat as it cooks. Drain any excess fat and set aside.
03 -
In the prepared baking dish, arrange a single layer of sliced potatoes. Season with salt and pepper. Top with 1/4 of the cooked beef and onion mixture, then sprinkle with 1/4 of the grated cheddar cheese. Repeat this layering process three more times.
04 -
In a small mixing bowl, combine the condensed cheddar soup, evaporated milk, milk, and garlic powder. Whisk until smooth.
05 -
Pour the sauce evenly over the assembled layers. Cover the dish tightly with aluminum foil and bake in the preheated oven for 60 minutes. After this initial baking period, remove the foil and continue to bake for an additional 15 minutes, until golden brown and bubbling.
06 -
Remove from oven and allow the casserole to stand for several minutes before serving to ensure it sets properly.