2. Prepare white sauce: In 2-qt. saucepan over medium heat, into hot vegetable oil, stir flour until blended; cook 1 minute. Gradually stir in milk; cook, stirring constantly, until mixture boils and thickens.
3. Into corn mixture remaining in bowl, stir chicken, black beans, cilantro, 1 cup shredded cheese, and half the white sauce.
4. Arrange half the tortillas over corn mixture; top with the chicken mixture. Arrange remaining tortillas over chicken mixture; top with remaining white sauce, then remaining cheese.
5. Bake casserole 30 to 35 minutes until hot in the center and bubbling around the edges. Let stand 15 minutes for easier serving. Garnish with chopped cilantro.