Preheat the oven to 350°F (175°C).
If your chicken is not cooked, season and cook the 2 chicken breasts in a skillet until fully cooked; shred and set aside in the skillet or an oven-safe pan.
Heat 1 tablespoon olive oil in the skillet over medium heat; add the diced red onion, chopped garlic, and diced red pepper and cook until the vegetables are crisp-tender, about 2 minutes.
Add the black beans, frozen corn, and the 16 ounces salsa or enchilada sauce to the skillet with the shredded chicken; stir to combine and remove from heat.
In a medium bowl, whisk together the remaining 2 tablespoons olive oil, cornmeal, white whole-wheat flour, coconut sugar, baking powder, salt, and the egg until the mixture resembles coarse crumbs.
Evenly sprinkle the cornmeal mixture over the chicken mixture in the skillet, then top with the shredded cheddar cheese.
Bake in the preheated oven for 25–30 minutes, until the cheese is bubbly and lightly golden.
Garnish with chopped cilantro or scallions if using, then serve warm.