Step 1

For the sauce: In a saucepan over medium heat, combine the vegetable oil and flour. Cook, whisking, until it begins to bubble; let it bubble for 1 minute. Pour in the enchilada sauce, chicken broth, cumin and some salt and pepper. Raise the heat and bring to a boil. Reduce to a simmer while you prepare the meat.

Step 2

For the meat: Brown the ground beef with the garlic and onions in a large skillet over medium-high heat, 5 to 8 minutes. Drain the fat and stir in the cumin and salt to combine. Stir the meat into the simmering sauce and shut off the heat.

Step 3

For the casserole: Preheat the oven to 350 degrees F. Lightly grease one 9-by-13-inch aluminum foil baking dish and one 9-by-13-inch glass baking dish with cooking spray.

Step 4

Break up the chips by crushing the bag slightly with your hands. Make sure not to over crush the chips; you're looking for pieces, not crumbs. Mix together the cheeses in a medium bowl.

Step 5

Divide a third of the broken chips between the prepared baking dishes. Top each with a quarter of the beef mixture and 2/3 cup of the cheese. Repeat, adding another layer of chips, beef mix and cheese to each. Finish by dividing the remaining chips between the baking dishes. Top each with 2/3 cup cheese.

Step 6

Cover the glass baking dish with foil and bake for 25 minutes. Remove the foil and continue to bake until bubbly, another 15 to 20 minutes.

Step 7

For the toppings: Top the cooked casserole with the shredded romaine, diced Roma tomatoes, sour cream and sliced black olives and green onions before serving.

Step 8

Allow the aluminum foil baking dish to cool completely while the other is baking. Once cool, wrap tightly in plastic wrap and foil. Transfer to the freezer.

Step 9

To bake from frozen, preheat the oven to 350 degrees F.

Step 10

Unwrap the baking dish and re-cover with foil. Bake, covered, for 35 to 40 minutes. Uncover and bake until bubbly, 15 to 20 minutes. Top with another batch of the toppings.