Preheat the oven to 375°F (190°C). Grease a 9x13-inch or similar baking dish with cooking spray or a little oil.
Trim any excess fat from the chicken. Place each piece between plastic wrap or parchment and pound to about 1/2-inch thickness for even cooking.
Sprinkle half of the taco seasoning evenly over both sides of the chicken and rub it in.
Heat the olive oil in a large skillet over medium-high heat. Sear the seasoned chicken 2–3 minutes per side, until lightly golden; it does not need to be fully cooked. Transfer the chicken to the prepared baking dish.
In a large bowl, combine the drained black beans, fire-roasted diced tomatoes, drained Mexicorn, diced green chilies, minced garlic, and the remaining taco seasoning. Stir until evenly mixed.
Spread the bean and tomato mixture evenly over the chicken in the baking dish, then sprinkle the shredded Colby or Mexican blend cheese on top.
Bake uncovered for 35–40 minutes, or until the chicken reaches 165°F (74°C) and the cheese is melted and bubbly.
Remove from the oven, squeeze the lime juice over the top, and serve with cilantro, sour cream, hot sauce, diced avocado, or other desired toppings.