01 -
Slice the potatoes into ⅛-inch thick slices and place them in water to prevent browning while preparing the other ingredients.
02 -
Preheat the oven to 350°F. Spray a 9x13 baking dish with nonstick cooking spray.
03 -
In a large saucepan or Dutch oven over medium-high heat, brown the lean ground beef, onions, and garlic. Break up the beef while cooking, and drain any excess oil.
04 -
In a medium-sized mixing bowl, whisk together the cream of mushroom soup, half and half, onion powder, kosher salt, and pepper.
05 -
Drain the water from the potatoes and start layering the casserole. Place ⅓ of the sliced potatoes in the bottom of the baking dish, followed by ⅓ of the ground beef, ¾ cup of shredded cheese, and ⅓ of the soup mixture.
06 -
Repeat the layering process two more times, ensuring the final layer is topped with 1½ cups of shredded cheese.
07 -
Cover the dish tightly with aluminum foil and bake for 1 hour and 10 minutes. Remove the foil and bake for an additional 20 minutes until the cheese is melted and bubbly.
08 -
Allow the casserole to rest for 15 minutes before serving as it will be very hot.