Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish using cooking spray and set it aside.

Start the enchilada sauce by warming the olive oil in a large skillet over medium heat. Add the chopped onion and 1/2 teaspoon of kosher salt. Sauté until the onion softens and becomes translucent, around 5 minutes.

While the sauce onion cooks, place the ground beef in a separate skillet over medium heat. Break it apart and season with salt and black pepper. Add the second chopped onion and cook until the beef is browned and fully cooked, approximately 5 minutes.

To the sautéed onions in the sauce pan, stir in the chili powder and ground cumin. Let the spices toast for about 30 seconds. Sprinkle in the flour, stirring to coat. Gradually whisk in the chicken broth, followed by the tomato sauce and minced garlic. Allow the mixture to simmer gently for about 5 minutes, stirring occasionally until slightly thickened.

Once the beef is fully cooked, remove from the heat and discard any excess fat. Fold in the green chiles and black beans, mixing until evenly combined.

Optional: Transfer the prepared enchilada sauce to a blender and puree until smooth for a refined texture.

Spoon 1/2 cup of the enchilada sauce into the bottom of your prepared baking dish and spread it out evenly. Pour another 1/2 cup of the sauce into the beef mixture and stir to combine.

Dip 6 corn tortillas into the remaining sauce, ensuring they are coated, then lay them across the bottom of the baking dish to form the first layer.

Distribute half of the beef and bean mixture over the tortillas. Sprinkle with 1 cup of shredded cheese.

Repeat the process with the final 6 tortillas, dipping them in sauce before layering. Spread the remaining beef mixture over them, then top generously with the remaining 2 cups of Colby Jack cheese.

Bake uncovered for 20 minutes, or until the cheese has melted completely and is bubbling at the edges.