Add the ground beef to a large skillet along with the onion and pepper and cook over medium heat, breaking up the meat as it cooks, until browned and cooked through.
Add the beans, tomatoes, taco seasoning, and cheese to the beef and stir to combine.
Set aside while you make the cornbread.
To make the cornbread:
Preheat oven to 400 degrees and butter a 12-inch cast iron skillet or 9x9 baking dish.
Add the cornmeal, flour, sugar, baking powder, baking soda, and salt to a mixing bowl and whisk together to combine.
Add the buttermilk and eggs to a small bowl and whisk well to combine.
Add the buttermilk mixture to the cornmeal mixture, along with the corn and chiles, and stir well to combine.
Let the mixture set for 10 minutes for the cornmeal to soften.
Spread half of the cornbread batter into the prepared baking dish and top with the beef mixture. Spoon the remaining cornbread batter over the top of the beef.
Bake for 35-40 minutes or until the cornbread is golden brown and cooked through.