HEAT oven to 375ºF.
BROWN meat with onions and peppers in large skillet on medium-high heat. Stir in chili powder; cook 1 min. Add salsa and corn; mix well. Simmer 5 min.
SPREAD 2 cups meat sauce onto bottom of 13x9-inch baking dish; top with layers of 2 tortillas, 1 cup meat sauce, sour cream and 1/2 cup cheese. Cover with 2 tortillas, 2 cups of remaining meat sauce and half of remaining cheese; top with remaining tortillas and meat sauce. Cover with foil.
BAKE 30 min. or until casserole is heated through. Top with remaining cheese; bake, uncovered, 5 min. or until melted.
We had this tonight for dinner. very fast and easy. very good, too, I might add. I didn't have the whole wheat tortillas but the floured ones worked just as well. Since there's just Robert and me, I used the old small PC deep dish baker and the tortilla worked perfectly well, size well...which of course I know none of you need to do.