Preheat the oven to 375°F and spray an 8 x 12 inch baking dish with cooking spray. Set aside.
In a skillet over medium-high heat, sauté the diced onion and red bell pepper in a couple of drizzles of olive oil for 3 minutes until they soften and begin to brown. Season with salt and black pepper to your taste.
Add the minced garlic and sauté for an additional minute. Add the ground beef. Season lightly with salt and black pepper. Cook until no pink remains in the ground beef and then drain any excess fat from the pan.
To the pan add the Rotel tomatoes, tomato sauce and taco seasoning. Cook for 3 minutes.
Add the Mexican corn and cilantro. Mix well then remove from the heat.
Pour into the prepared baking dish and sprinkle with 1¼ cups of shredded Colby-Jack cheese.
Green Chili Cornbread Topping:
In a medium mixing bowl, whisk together both packages of cornbread mix, buttermilk, egg, melted butter, and green chili peppers. Stir in ¾ cup Colby-Jack cheese. Spread evenly over the filling.
Bake for 30 minutes until the top is golden and a toothpick inserted into the center comes back clean. Rest for 5 minutes then serve.