In a skillet over medium heat, add the ground beef and chopped onion. Cook until browned and the onion is translucent, about 7-10 minutes. Drain excess grease.

Wash and slice your potatoes thinly, about 1/8-inch thick, and set aside.

Layer half of the sliced potatoes in the crockpot, followed by half of the ground beef mixture and a sprinkle of cheddar cheese. Repeat layers ending with cheese on top.

Whisk together cream of mushroom soup, milk, garlic powder, salt, and pepper in a mixing bowl, then pour over the layers.

Cover and cook on low for 6 to 8 hours, or until potatoes are fork-tender and cheese is melted.

In the last 15 minutes, add the remaining cheddar cheese on top and cover to melt.