Heat a skillet over medium heat and cook the ground beef along with the chopped onion for about 5-7 minutes, stirring occasionally, until browned and no pink remains. Drain any excess fat.

Wash and thinly slice your potatoes to about 1/8 inch thick.

Layer half of the sliced potatoes in the bottom of the crockpot. Add half of the cooked beef and onion mixture, followed by a portion of the shredded cheddar cheese. Repeat the layers with the remaining ingredients.

In a separate bowl, whisk together the cream of mushroom soup, milk, garlic powder, salt, and pepper until well combined. Pour this mixture evenly over the layered ingredients in the crockpot.

Cover the crockpot and cook on low for 6 to 8 hours or until the potatoes are tender.

About 15 minutes before serving, top the casserole with the remaining shredded cheddar cheese. Cover again to allow the cheese to melt.

Before serving, sprinkle fresh parsley or chopped chives on top.