Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Peel and thinly slice the potatoes (about ⅛-inch thick). Set aside.
Heat a large skillet over medium heat. Add the ground beef and cook until browned.
Stir in the diced onion and garlic, cooking for 3–4 minutes until softened. Drain excess grease if needed.
In a medium bowl, whisk together the cream of mushroom soup, sour cream, milk, paprika, onion powder, garlic powder, salt, and pepper until smooth.
Arrange half of the sliced potatoes in an even layer in the prepared baking dish.
Spread half of the cooked beef mixture over the potatoes.
Spoon half of the creamy sauce over the beef and spread evenly.
Sprinkle with 1 cup of shredded cheddar cheese.
Repeat the layers with the remaining potatoes, beef, sauce, and cheese.
Cover tightly with aluminum foil and bake for 60 minutes.
Remove the foil and continue baking for 15–20 minutes, or until the potatoes are fork-tender and the cheese is golden and bubbly.
Let the casserole rest for 10 minutes before serving.
Garnish with parsley, green onions, or crispy fried onions if desired