01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with cooking spray or a small amount of oil.
02 - Heat a large skillet over medium heat. Add ground beef and cook, breaking it up with a wooden spoon, until browned completely, approximately 5 minutes. Drain excess fat from the skillet.
03 - Add diced onion to the beef and sauté for 3 minutes until softened. Stir in minced garlic and cook for 1 minute until fragrant.
04 - Add chili powder, ground cumin, smoked paprika, salt, black pepper, corn kernels, and black beans if using. Stir well to combine spices evenly. Cook for 2 minutes to meld flavors, then remove from heat.
05 - Spread 1/2 cup enchilada sauce evenly across the bottom of the prepared baking dish.
06 - Arrange 4 tortillas over the sauce, overlapping as necessary to cover the bottom. Spoon half of the beef mixture over the tortillas and top with 1/3 of the shredded cheese blend.
07 - Pour 1/2 cup enchilada sauce over the first beef layer. Place the remaining 4 tortillas on top, followed by the rest of the beef mixture and another 1/3 of the cheese.
08 - Pour the remaining enchilada sauce over the casserole, ensuring even coverage. Sprinkle the remaining cheese on top.
09 - Cover the baking dish tightly with aluminum foil. Bake for 25 minutes to heat through and meld flavors.
10 - Remove foil and continue baking for an additional 10 minutes until the cheese is bubbly and lightly golden on top.
11 - Let the casserole rest for 10 minutes before slicing. This allows layers to set and makes serving easier. Garnish with cilantro, tomatoes, jalapeños, and sour cream as desired.