How to Make Chicken Poblano Casserole:

• Start by preheating the broiler. Halve the poblanos and bell pepper lengthwise, removing seeds and membranes. Arrange them skin side up on a foil-lined baking sheet, flattening with your hand. Add the corn to the sheet and broil for 10 minutes until the poblanos and bell peppers are blackened and blistered, and the corn is lightly browned. Alternatively, you can roast them individually over a gas stove flame using tongs. Place the roasted poblanos and bell pepper in a sealed plastic bag for 10 minutes, then peel and chop them coarsely, keeping poblanos and bell pepper separate. Remove the corn kernels from the cobs and take this opportunity to cut up the chicken breast.
  3 (12 oz.) poblano or pasilla peppers*, 1 large (8 oz.) red bell pepper, 3 ears corn**
• In a large saucepan, combine flour, 1/2 teaspoon salt, and black pepper. Gradually add milk before applying heat, stirring constantly. Cook over medium heat until slightly thick (about 12 minutes), ensuring it coats the back of a spoon. In a food processor or blender, combine 1 cup of the milk mixture with the poblanos, processing until smooth. Stir this pureed poblano mixture into the remaining milk mixture.
  1/3 cup all-purpose flour, 1 tsp. table salt, 1/4 tsp. ground black pepper, 3-1/2 cups whole milk
• Preheat the oven to 350 degrees F.
• In a large bowl, combine bell pepper, corn, remaining 1/2 teaspoon salt, 1 cup Mexican cheese, red onion, cilantro, eggs, and ricotta.
  3 cups (12 oz.) Mexican cheese blend, divided, 1/3 cup chopped red onion, 1/3 cup chopped fresh cilantro, 2 large eggs, lightly beaten, 1 tub (15 oz.) ricotta cheese
• Coat the bottom of a 13 x 9-inch baking dish with cooking spray. Spread 1/2 cup of the sauce in the bottom of the dish. Arrange 6 tortillas over the sauce, slightly overlapping. Spread half of the ricotta mixture over the tortillas, top with half of the chicken, and sprinkle with 1/3 cup green onions and 2/3 cup Mexican cheese. Pour about 1 cup of sauce over the cheese. Repeat the layers with 6 tortillas, the remaining ricotta mixture, the remaining chicken, 1/3 cup green onions, 2/3 cup Mexican cheese, 1 cup sauce, and 6 tortillas. Pour the remaining sauce over the tortillas. Coat one side of foil with cooking spray, place it coated side down over the casserole, and bake at 350 for 30 minutes. Uncover, sprinkle with the remaining 2/3 cup Mexican cheese and 1/3 cup green onions, and bake, uncovered, for an additional 15-20 minutes or until the cheese melts and is slightly golden brown.
  cooking spray, 18 (6-inch) white corn tortillas, 3-3/4 cups chopped, cooked chicken breast, 1 cup thinly sliced green onion, divided
• Let it stand for 15 minutes before serving.