Preheat your oven to 350°F (175°C) and coat a 9x13-inch baking dish with cooking spray.

Heat a tablespoon of oil in a skillet over medium heat, add diced onion and sauté for about 5 minutes until translucent.

Sprinkle in chili powder and cumin, stir for 30 seconds until fragrant, then add the flour and mix to create a roux.

Gradually pour in chicken stock and tomato sauce while stirring continuously to avoid lumps, then add minced garlic and let it simmer for about 5 minutes.

In a separate skillet, cook ground beef over medium heat and drain excess fat, then mix in sautéed onions and cook for an additional 5 minutes.

Combine green chiles and black beans with half of the enchilada sauce into the cooked beef and stir well.

Spread 1/2 cup of enchilada sauce in the baking dish, dip six corn tortillas in the sauce and layer them at the bottom.

Add half of the beef mixture and a sprinkle of cheese on top, then repeat with another layer of tortillas and the remaining filling, finishing with cheese.

Bake the casserole in the preheated oven for 20 minutes until the cheese is bubbly and golden brown.

Remove from the oven and let cool for a few minutes before serving.