Heat oven to 400°F. Spray 8-inch square (2-quart) glass baking dish with cooking spray. In 10-inch skillet, cook beef and onion with seasoning over medium heat, stirring frequently, until brown; drain. Stir in ketchup.
Spoon beef mixture into baking dish; top with shredded cheese.

Meanwhile, place frozen potatoes on ungreased large cookie sheet; bake 10 minutes. Top casserole evenly with potatoes. Bake 20 to 25 minutes or until heated through and potatoes are golden brown. Sprinkle with bacon during last 5 minutes of bake time. Top with pickle slices.