Pre-heat oven to 350°F.
In a large skillet, over medium heat, cook beef and onion; 6 to 8 minutes or until beef is no longer pink and onion is tender; crumble meat as it cooks; drain.
Stir in beans; heat through.
Reserve 1 cup corn chips for topping; place remaining corn chips in a greased 9-inch x 13-inch baking dish.
Layer with meat mixture, enchilada sauce and cheese; top with reserved chips.
Place in the pre-heated oven and bake, uncovered, 15 to 20 minutes or until cheese is melted.
Remove from oven; sprinkle with green onions; serve.
