Preheat oven to 350°F. Spray a 9x13-inch baking dish with cooking spray and set aside.

In a large skillet for the enchilada sauce, heat 1 tablespoon oil over medium heat. Add diced onion and kosher salt. Saute until translucent, about 5 minutes.

In a separate skillet, cook ground beef (or chicken), seasoning with salt and pepper. Add diced onion and cook until meat is cooked through, about 5 minutes.

Stir chili powder and cumin into onion for the enchilada sauce, cook for about thirty seconds. Then stir in all-purpose flour. Slowly whisk in chicken stock, then add tomato sauce and minced garlic. Simmer for 5 minutes.

Once beef (or chicken) is cooked, remove from heat, drain fat, and stir in green chiles and black beans.

Optionally, transfer enchilada sauce to a blender and blend until smooth. Pour 1/2 cup sauce into the bottom of prepared baking dish. Pour 1/2 cup of sauce into the beef (or chicken) mixture.

Dip 6 tortillas in remaining sauce to coat and line the bottom of the casserole dish. Divide beef (or chicken) mixture in half, add half on top of tortillas, and top with 1 cup cheese.

Dip remaining 6 tortillas in sauce and top with remaining beef (or chicken) mixture and 2 cups Colby Jack cheese.

Bake uncovered for 20 minutes or until cheese is bubbly.