Begin by browning the ground beef in a skillet over medium heat. Break it apart with a spatula to ensure even browning and drain any excess fat once fully browned.

Wash and slice the russet or Yukon gold potatoes into thin discs, about 1/8 inch thick. Set the sliced potatoes aside.

Chop the medium onion into small pieces and set aside.

In a mixing bowl, combine the cream of mushroom soup with the milk and garlic powder. Whisk until smooth.

Layer half of the sliced potatoes at the bottom of the Crockpot, followed by half of the chopped onions and half of the cooked ground beef.

Pour half of the cream of mushroom soup mixture over the first layer, and sprinkle one cup of shredded cheddar cheese on top.

Repeat the layering process with the remaining ingredients, finishing with the remaining cheddar cheese on top.

Cover the Crockpot and cook on low for 6 to 8 hours or high for 3 to 4 hours until potatoes are soft and the casserole is bubbly.