01 - Preheat the oven to 375°F. Grease a 9x13-inch baking dish with cooking spray or oil.
02 - In a large skillet over medium-high heat, cook ground beef until browned, breaking up with a spoon, about 5 minutes. Drain excess fat if necessary.
03 - Add chopped onion to the beef and cook 3 to 4 minutes until softened. Stir in garlic, cumin, chili powder, smoked paprika, salt, and black pepper; cook 1 minute until fragrant.
04 - Stir in 1/2 cup of the enchilada sauce into the beef mixture. Remove skillet from heat.
05 - Spread 1/2 cup enchilada sauce on the bottom of the prepared baking dish.
06 - Arrange 5 tortillas across the sauce, tearing pieces as necessary to cover completely.
07 - Spread half of the beef mixture evenly over the tortillas. Top with 1 cup shredded cheddar and 1/2 cup shredded Monterey Jack cheese.
08 - Add remaining tortillas over the beef layer, spread with 1/2 cup enchilada sauce, then top with remaining beef mixture and cheeses.
09 - Pour remaining 1/2 cup enchilada sauce evenly on top. Sprinkle any reserved cheese over the surface.
10 - Cover dish with aluminum foil and bake for 20 minutes. Remove foil and bake uncovered for an additional 10 to 15 minutes until cheese is bubbly and golden.
11 - Remove casserole from oven and let rest for 5 to 10 minutes. Garnish with sour cream, cilantro, diced avocado, and sliced green onions as desired. Serve warm.