In a large bowl, combine ground beef, oats, 2/3 cup chili, egg, 1/4 cup scallions, salt and pepper; mix lightly but thoroughly then press the mixture evenly into a 9-inch round metal cake pan.
Bake for 45-50 minutes or until center of meatloaf registers 160° on an instant-read thermometer; remove from oven and set aside.
Place remaining chili in a microwave-safe bowl; cover and heat on high for 1-2 minutes.
Drain any juices from meatloaf and discard.
Top drained meatloaf with hot chili; sprinkle with cheese; bake 5 minutes longer or until cheese has melted.
Let meatloaf stand 5 minutes before cutting; top with remaining 1/4 cup scallions.