Preheat the oven to 350degrees F.
For the sauce: In a saucepot over medium heat, add the oil, onions and a pinch of salt. Saute until the onions are tender and translucent. Add the tomato paste at this point and turn the heat up a bit, if needed, to cook the paste. Stir and cook until it deepens in color, and then add the cumin, thyme and garlic. Stir to blend and cook until fragrant. Then add the beef broth and crushed tomatoes. Raise the heat to bring the mixture to a boil, and then lower to a simmer and cover, simmering for 20 minutes more. (The sauce can be stored and frozen at this point.)
For the beef filling: Meanwhile, in a large pan with straight sides, add the olive oil over medium-high heat. When the oil begins to swirl, add the onions and green and yellow bell peppers. Add the garlic and cook until tender, about 4 minutes more. Add the ground beef, broth, cumin, onion powder, thyme, tomatoes and Spanish seasoning, allowing time between each addition to blend. Season with a pinch of salt and a grind or 2 of pepper (the Spanish seasoning adds salt content, so be careful to not over season). Stir and break down the beef into bits using a spoon or fork. Cook until the beef is cooked through, 8 to 10 minutes. (The beef can be stored and frozen at this point.)
To assemble the casserole: Toss the shredded cheeses together to blend and set aside. Add 1/2 cup of the red sauce to a 9 1/2-inch deep-dish baking dish and spread to coat the bottom evenly. Top with 6 tortillas, overlapping to cover the bottom of the casserole dish. Layer the dish by next adding half of the beef mixture and 1/2 cup of the shredded cheeses, spreading evenly in the casserole. Next, dunk 6 tortillas, one by one, in the warm red sauce and layer over the cheese and beef, overlapping where needed. Top with the remaining beef, another 1/2 cup of the shredded cheeses and another layer of tortillas dunked in the red sauce. Pour the rest of the sauce over the top, spread evenly and finish with the remaining shredded cheese. Place dish on a baking sheet and bake until the cheese is melted and the sauce bubbles, 25 to 30 minutes. If baking the dish from the freezer, add 15 to 20 minutes to the cook time, or until it's bubbly. Cover loosely with foil if it's browning too quickly. Serve hot.
This recipe has been updated and may differ from what was originally published or broadcast.