Preheat the oven to 350°F. Spray a 9×13-inch baking dish with non-stick cooking spray and set aside.

In a medium skillet over medium heat, add 1/4 cup olive oil, 2 Tablespoons flour, and 3 Tablespoons chili powder. Whisk continuously until the mixture is fragrant and light brown, about 1–2 minutes.

Slowly whisk in 1 (15 ounce) can tomato sauce, 1 1/2 cups vegetable stock, 1 teaspoon cumin, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder. Bring to a simmer and cook, whisking occasionally, until the sauce thickens slightly, a few minutes.

Remove the sauce from heat, season with salt and pepper to taste, and set the sauce aside.

Heat a large skillet over medium-high heat. Add 1 pound lean ground beef and sprinkle with 1 teaspoon salt and 1 teaspoon ground pepper. Cook, breaking the meat into pieces, until browned and no longer pink, about 6–8 minutes.

Add 1/2 medium white onion (diced) and 1 green bell pepper (diced) to the beef. Cook until the onion is translucent, about 4–5 minutes.

Add 3 cloves garlic (minced) and 1 (15 ounce) can black beans (drained). Cook, stirring, for 2–3 minutes. Remove the beef and vegetable mixture from the heat.

In a medium bowl, combine 2 cups shredded pepper jack cheese and 1 cup shredded Monterey jack cheese.

Pour about 1/4 cup of the prepared enchilada sauce into the bottom of the prepared baking dish and spread it to coat the bottom.

Line the bottom of the dish with the first 6 six-inch corn tortillas, slightly overlapping as needed.

Spread half of the beef mixture evenly over the tortillas, then sprinkle half of the combined cheeses over the beef.

Place the second set of 6 six-inch corn tortillas in a single layer over the cheese.

Split the remaining prepared enchilada sauce (the sauce left after the initial 1/4 cup) into two equal portions. Pour one portion evenly over the second layer of tortillas and reserve the other portion.

Spread the remaining beef mixture over the sauce on the tortillas. Pour the reserved portion of enchilada sauce evenly over the beef.

Sprinkle the remaining cheese evenly over the top of the dish.

Cover the baking dish with foil and bake at 350°F for 20 minutes. Remove the foil and bake an additional 15–20 minutes, or until the cheese is bubbly and beginning to brown.

Remove the enchilada pie from the oven and let it rest at room temperature for about 10 minutes before cutting and serving.