Cook ground turkey and onion in a nonstick skillet over medium-high heat until turkey is browned, stirring until it crumbles. Remove from heat; add cumin and next 5 ingredients to skillet. Stir well, and set mixture aside.
Arrange half of green chile quarters in an 11- x 7- x 1-1/2-inch baking dish coated with cooking spray; top with half of cheese. Spoon bean mixture in mounds onto cheese, and spread gently, leaving a 1/4-inch border around edge of dish; top with corn. Arrange remaining chile strips over corn; top with remaining cheese. Set aside.
Combine flour and 1/4 teaspoon salt in a bowl; gradually add milk and hot sauce, stirring with a wire whisk until blended. Stir in eggs and egg whites; pour over casserole. Bake, uncovered, at 350 degrees for 1 hour and 5 minutes or until set; let stand 5 minutes. Cut into squares to serve.