Spray a large skillet with cooking oil and set it over medium-high heat. Add the ground chicken and cook, crumbling it as it browns, until no longer pink, about 5 minutes. Transfer to a plate. Add the olive oil and swirl to coat the pan. Add the onions and peppers and cook, stirring frequently, until just beginning to soften, about 3 minutes. Add the garlic and cook until fragrant, 30 seconds. Return the chicken to the pan and add the cumin, chili powder, and salt, stirring to coat the chicken and vegetables in the spices. Add the tomato sauce, green chiles, and corn, and bring to a boil. Reduce the heat and simmer, stirring occasionally, 8 minutes. Divide chicken mixture evenly among the ramekins.
In a small saucepan, combine the cornmeal with the chicken broth and bring to a boil over medium heat, stirring constantly, then reduce the heat and simmer, still stirring constantly, until thickened, 6 minutes. Remove the pan from heat and stir in the cheese. Divide the cornmeal mixture evenly among the ramekins, smoothing the tops with the back of a spoon. Bake until the cornmeal crust is light golden brown, 18 to 20 minutes. Top each ramekin with sour cream and chopped fresh cilantro, if desired, and serve!