Cook Beef:
Preheat oven to 400°F (200°C). In a large skillet, cook ground beef and diced onion over medium heat until beef is browned and onions are tender. Drain excess fat. Season with garlic powder, salt, and pepper.

Assemble:
Spread frozen French fries evenly in a greased 9×13-inch baking dish. Top with cooked ground beef mixture. Sprinkle shredded cheddar cheese over the top.

Bake:
Bake for 25–30 minutes or until fries are crispy and cheese is melted and bubbly.

Add Toppings:
Drizzle ketchup and mustard over the baked dish. Sprinkle chopped pickles and green onions if desired.

Serve:
Serve warm as a delicious cheeseburger-inspired casserole.