Preheat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned. Drain any excess grease.
Stir in the minced garlic and cook for 30 seconds.
In a bowl, whisk together the cream of mushroom soup, milk, Worcestershire sauce, garlic powder, onion powder, paprika, thyme, salt, and black pepper.
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.
Pour half of the soup mixture over the beef and potatoes.
Sprinkle with 1 cup of shredded cheddar cheese.
Repeat the layers with the remaining potatoes, beef, soup mixture, and cheese.
Cover tightly with aluminum foil.
Bake for 60 minutes.
Remove the foil and continue baking for 20 to 25 minutes, or until the potatoes are fork-tender and the cheese is bubbly and golden.
Let the casserole rest for 10 minutes before serving.
Garnish with chopped parsley and serve warm.