Cut tamales into 3/4-in. slices. Place in a greased shallow 1-qt. baking dish. Top with half of the chili and onion. Sprinkle with 1/3 cup corn chips and shredded cheese. Top with remaining chili and onion.
Cover and bake at 350° for 30 minutes. Uncover; sprinkle with the remaining corn chips. Arrange cheese slices over top. Bake 5-10 minutes longer or until chips are crisp and cheese is melted.