In a skillet, heat olive oil over medium heat. Add chopped onion and minced garlic, and cook until softened.
Add ground turkey to the skillet and cook until browned. Stir in cumin, chili powder, salt, and black pepper.
In a baking dish, layer corn tortillas, ground turkey mixture, black beans, corn, enchilada sauce, and shredded cheese. Repeat layers until all ingredients are used, ending with a layer of cheese on top.
Bake in the preheated oven for 25-30 minutes, or until the cheese is melted and bubbly.
Let the casserole cool for a few minutes before serving with a dollop of sour cream on top.
Notes:
Feel free to add your favorite toppings like avocado, cilantro, or jalapeños.