Preheat the oven: Set your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
Soften the veggies: Heat olive oil in a skillet over medium.
Add onion and bell pepper. Sauté 4–5 minutes, until softened and lightly golden.
Season the base: Stir in cumin, chili powder, smoked paprika (if using), salt, and pepper. Cook 30 seconds to bloom the spices.
Build the filling: Add shredded chicken, black beans, and corn to the skillet.
Pour in 1 cup of enchilada sauce and mix until coated. Off the heat, fold in 1/2 cup sour cream or Greek yogurt if using. Taste and adjust seasoning.
Prep the tortillas: If using corn tortillas, warm them briefly in a dry skillet or microwave (wrapped in a damp towel) so they bend without cracking.
Layer 1: Spread 1/3 cup enchilada sauce on the bottom of the baking dish.
Arrange a layer of tortillas to cover (tear to fit if needed). Spoon half the chicken mixture over the tortillas. Sprinkle with 3/4 cup cheese.
Layer 2: Add another layer of tortillas, the remaining chicken mixture, and another 3/4 cup cheese.
Top layer: Finish with a final layer of tortillas, the remaining enchilada sauce, and the rest of the cheese (about 1 cup).
Bake: Cover loosely with foil (tent it so it doesn’t stick to the cheese).
Bake 20 minutes. Remove foil and bake 8–12 minutes more, until bubbly and lightly browned.
Rest and garnish: Let it rest 10 minutes so it sets and slices cleanly. Top with chopped cilantro and green onions.
Serve: Cut into squares.
Serve with lime wedges, extra sour cream or yogurt, and your favorite hot sauce.