In A Large Bowl, Combine Soup Mix, Ketchup, Brown Sugar, Horseradish And Chili Powder. Crumble Beef Over Mixture; Mix Well. Shape Into 10 Patties. Grill, Broil Or Pan-Fry Until The Meat Is No Longer Pink. Cut Eyes, Nose And Mouth Out Of Each Cheese Slice To Create A Jack-O-Lantern. Place Cheese On Burgers; Cook Until Cheese Is Slightly Melted, About 1 Minute. Serve On Buns.