Preheat oven to 375°F. Heat oil in a 12-inch cast-iron or medium ovenproof skillet over medium heat. Add onion, bell pepper, and garlic. Season with salt and pepper. Cook, stirring occasionally, until softened, 4 to 6 minutes.
Add beef and cook, just until browned, 5 to 7 minutes. Stir in 1 ½ cups corn, 2 teaspoons chili powder, enchilada sauce, and 1 cup Cheddar. Remove from heat.
Make cornbread according to package directions, adding hatch chiles, remaining ½ cup Cheddar, 2 teaspoons chili powder, and 1 cup corn to the mixture. Spread over beef mixture.
Bake until cornbread is cooked through, 42 to 45 minutes. Serve immediately.
