1. Preheat oven to 375°F (190°C) and grease a 9×13-inch baking dish.
2. In a skillet over medium heat, cook the ground beef and onion until the beef is browned and the onion is soft. Season with garlic powder, paprika, salt, and pepper. Set aside.
3. In a saucepan, melt butter over medium heat. Stir in flour and cook for 1 minute. Gradually add cream, whisking until thickened. Season with salt and pepper.
4. Layer half of the sliced potatoes in the prepared dish, top with half of the beef mixture, and pour over a portion of the cream sauce. Repeat layers and finish with shredded cheese on top.
5. Cover with foil and bake for 40 minutes. Remove foil and bake for an additional 15-20 minutes, or until potatoes are tender and cheese is bubbly.
6. Let rest for 10 minutes, garnish with parsley, and serve.