Preheat the oven: Set to 375°F (190°C).
Lightly grease a 9x13-inch baking dish.
Sauté the aromatics: Heat olive oil in a large skillet over medium heat. Add onion and bell pepper. Cook 4–5 minutes until softened.
Stir in garlic for 30 seconds.
Brown the turkey: Add ground turkey, breaking it up with a spoon. Cook until no longer pink, about 5–7 minutes. Season with salt and pepper.
Spice it up: Stir in chili powder, cumin, smoked paprika, and oregano.
Cook 1 minute to bloom the spices.
Add mix-ins: Stir in green chiles, black beans, and corn. Pour in 1 cup of enchilada sauce. Simmer 2–3 minutes to thicken slightly.
Taste and adjust seasoning.
Layer the casserole: Spread a thin layer (2–3 tablespoons) of enchilada sauce on the bottom of the baking dish. Add a layer of tortillas, tearing to fit so the bottom is mostly covered.
Build the first layer: Spoon half the turkey mixture over the tortillas. Sprinkle with one-third of the cheese.
Repeat: Add another layer of tortillas, the remaining turkey mixture, and another third of the cheese.
Top it off: Finish with a final layer of tortillas, the remaining cup of enchilada sauce, and the last of the cheese.
Press gently to settle.
Bake: Cover loosely with foil and bake 15 minutes. Remove foil and bake another 10–12 minutes, until the cheese is melted and bubbling around the edges.
Rest and garnish: Let it rest 8–10 minutes so it sets and slices cleanly. Sprinkle with chopped cilantro.
Add optional toppings as you like.
Serve: Cut into squares and serve warm with lime wedges. A simple side salad or rice works well.