Preheat the Oven: Preheat your oven to 350°F.
Cook the Beef and Onions: In a large oven-safe skillet or Dutch oven over medium heat, cook the ground beef and diced onions until the beef is no longer pink and the onions are tender.
Add the Garlic: Stir in the minced garlic and cook for an additional 2 minutes until fragrant. Drain any excess fat and return the mixture to the pan.
Build the Filling: Pour in the diced tomatoes, enchilada sauce, black beans, corn, cooked rice, and all the seasonings. Stir well to combine.
Simmer the Mixture: Bring the mixture to a gentle simmer, cover, and cook for 10 minutes until heated through, stirring occasionally.
Prepare the Cornbread: In a separate bowl, prepare the cornbread batter according to the package instructions.
Top with Cornbread and Bake: Pour the cornbread batter over the filling in the skillet, spreading it gently to cover the surface. Bake in the preheated oven for 25 minutes, or until the cornbread topping is golden brown and a toothpick inserted in the center comes out clean.
Serve and Garnish: Remove from the oven and let it set for about 5 minutes. Top with fresh cilantro and green onions before serving, if desired.