Finely dice the onion into 1/4-inch pieces and mince the garlic cloves. Dice the green bell pepper into similar-sized pieces. Measure out all dry spices (cajun seasoning, chili powder, cumin, garlic powder, pepper, and red pepper flakes) into a small bowl and stir to combine. Preheat your oven to 350°F and lightly grease a 9x13 inch baking dish or similar-sized casserole dish. This prep work ensures everything is ready when you need it and prevents scrambling mid-recipe.

Heat a large skillet over medium-high heat and add the ground beef, breaking it apart as it cooks. Add the diced onion to the beef and cook for 5-7 minutes, stirring occasionally, until the beef is deeply browned and the onion becomes translucent. This browning develops rich, savory flavors through the Maillard reaction. Once the beef is cooked through, add the minced garlic and green pepper, cooking for another 2 minutes until fragrant.

Carefully drain excess fat from the beef mixture, leaving about 1 tablespoon to keep the mixture moist and flavorful. I find that 80/20 ground beef renders just enough fat to create a rich base without being greasy. Return the beef to the pan over medium heat, then add the diced tomatoes, red enchilada sauce, black beans, corn, and the spice mixture from Step 1. Stir everything together thoroughly to distribute the spices evenly and create a cohesive sauce base.

Stir the rice into the beef and sauce mixture, combining it thoroughly so the grains absorb the flavors of the meat and sauce. Reduce heat to medium-low, cover the skillet with a lid or foil, and simmer for 10-12 minutes, stirring occasionally to prevent sticking. The rice will absorb liquid and cook partially; it doesn't need to be fully tender at this stage since it will finish cooking in the oven.

Pour the entire beef, rice, and sauce mixture into the prepared baking dish, spreading it into an even layer. Sprinkle the cheddar cheese evenly over the top, making sure to cover all the filling so it melts uniformly and creates a golden crust. For extra richness, I recommend using Sharp Cheddar—it has a more pronounced flavor that stands up beautifully against the bold enchilada spices.

Place the casserole in the preheated 350°F oven and bake for 20-25 minutes, until the cheese is melted, bubbly, and lightly golden around the edges. The casserole is ready when you see the cheese bubbling vigorously and the filling is heated through. Remove from the oven and let rest for 2-3 minutes—this brief rest allows the structure to set slightly, making it easier to serve.

Sprinkle the fresh cilantro and chopped green onions over the hot casserole just before serving. These bright, fresh toppings provide a vibrant contrast to the warm, rich filling and add a pop of color and freshness to each bite. Serve directly from the baking dish or portion into bowls, making sure each serving gets a mix of the rice, filling, and melted cheese.