Fire up a comal on the stovetop. Rinse the chiles and pierce each with a knife. Place them on the comal and let them roast evenly. You will have to keep an eye on them, making sure to turn them over until all sides are roasted. When done, the skins should be evenly blistered and mostly black.
Place roasted chiles into a plastic bag and close the bag. Cover the plastic bag with a kitchen towel. The steam will help the blackened skin to separate. When cool, rub off the blackened skin, careful to keep the stem intact on the chiles.
Using a small sharp knife, carefully slit chiles open along 1 side. Remove seeds, leaving stems attached. Set aside to fill later.
Stuffing Chili Peppers
Preheat oven to 400 degrees F.
In a medium saucepan heat oil over medium-high. Add corn; cook and stir 2 minutes. Add chili powder; cook and stir 1 minute.
Add broth. Bring to boiling; reduce heat. Simmer, uncovered, 3 minutes. Remove from heat; cool 10 minutes. Stir in chicken, cheese, egg, salt, and black pepper.
Spoon ¼ cup of the filling onto each chile pepper.
Cilantro Cream Sauce:
In a small saucepan melt butter over medium. Add garlic and cook for 2 minutes, stirring occasionally.
Add flour, stirring until smooth. Add half-and-half. Cook and stir until thickened and bubbly. Cook and stir 1 minute more. Stir in cilantro. Season to taste with salt and pepper.
Coat a rectangular baking dish with cooking spray.
Pour Cilantro Cream Sauce in the prepared baking dish. Arrange peppers, filling sides up, in sauce.
Bake, uncovered, about 20 minutes or until filling is heated through.