Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish with a light coating of oil or nonstick spray.
Sauté the aromatics. Heat olive oil in a skillet over medium heat.
Add the onion and a pinch of salt, cooking 4–5 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
Mix the filling. In a large bowl, combine shredded chicken, sautéed onion and garlic, green chiles, corn, black beans, chili powder, cumin, smoked paprika, and sour cream. Season with salt and pepper.
Stir until evenly coated.
Warm the tortillas. Wrap the corn tortillas in a damp paper towel and microwave 30–45 seconds to soften. This prevents cracking.
Layer the casserole. Spread a thin layer of enchilada sauce over the bottom of the baking dish. Add a layer of tortillas, slightly overlapping to cover the base.
Spoon a third of the chicken mixture on top, drizzle with sauce, and sprinkle with cheese. Repeat for two more layers: tortillas, filling, sauce, cheese.
Finish with cheese. Ensure the top layer has a generous sprinkle of cheese and a light drizzle of sauce to prevent drying.
Bake. Cover with foil and bake for 20 minutes. Remove foil and bake another 10–15 minutes, until the cheese is melted and the edges are bubbly.
Rest and garnish. Let the casserole rest 10 minutes before slicing.
Top with chopped cilantro. Serve with lime wedges if you like a bright finish.