01 - Preheat the oven to 375°F. Lightly grease a 9x13 inch baking dish with nonstick spray or butter.
02 - In a large skillet over medium-high heat, cook the ground beef until fully browned, breaking it apart with a spoon as it cooks. Drain excess fat if necessary.
03 - Add the chopped onion, diced bell pepper, and minced garlic to the skillet. Sauté for 3 to 4 minutes until the vegetables are softened and fragrant.
04 - Stir in the uncooked rice, frozen corn if using, paprika, dried oregano, black pepper, and salt. Cook for 1 minute, stirring constantly, to toast the rice slightly and bloom the spices.
05 - Pour in the diced tomatoes with their juice and the beef broth. Stir well to combine all ingredients. Bring the mixture to a gentle simmer.
06 - Remove the skillet from heat. Fold in 1 cup of the shredded cheddar cheese and the sour cream until evenly distributed throughout the mixture.
07 - Transfer the mixture into the prepared baking dish, spreading it into an even layer. Sprinkle the remaining 1 cup of shredded cheddar cheese uniformly over the top.
08 - Cover the dish tightly with aluminum foil and bake for 25 minutes. Remove the foil and continue baking for an additional 15 minutes, or until the cheese is bubbly and golden and the rice is tender.
09 - Remove from the oven and let the casserole stand for 5 minutes to allow the flavors to settle and the dish to set before serving.