1Heat oven to 350°F. In 12-inch nonstick skillet, cook beef and onion over medium-high heat 5 to 7 minutes, stirring occasionally, until thoroughly cooked; drain. Reserve 1/4 cup enchilada sauce; set aside. Add remaining enchilada sauce, corn and chiles to beef mixture. Stir in cumin and chili powder. Reduce heat to medium-low; simmer uncovered 5 minutes.
2Spray 9-inch round (2-quart) glass baking dish with cooking spray. Place 1 tortilla in casserole; top with about 3/4 cup of the beef mixture and 3 tablespoons of the cheese. Repeat layers 3 times. Top with remaining tortilla, the reserved enchilada sauce and the remaining cheese.
3Bake, uncovered, 30 to 40 minutes or until hot and cheese is melted. Cool 5 minutes. Serve with sour cream.