Tip: Another "Mexican Lasagna" recipe ranks higher.
Heat oven to 375.
Brown meat, onions and peppers in a large skillet on medium-high heat. Stir in chili powder; cook 1 min. Add salsa and corn; mix well. Simmer 5 min.
Spread 1C meat sauce onto bottom of 8 or 9" square baking dish; top with layers of 1 tortilla, 1/2C meat sauce, sour cream and 1/4C cheese. Cover with 1 tortilla, 1C remaining meat sauce and 14 C of remaining cheese; top with remaining tortilla and meat sauce. Cover with foil.
Bake 25 min. or until casserole is heated through. Top with remaining cheese; bake, uncovered, 5 min. or until melted