Preheat the oven to 350 degrees F. Lightly grease a 9x13 inch casserole dish with cooking spray and set aside.
In a Dutch oven or heavy bottom saucepan, cook the chorizo, starting over low heat to render out the fat. Once there's fat in the pan, turn up the heat to medium and continue to cook, breaking up any larger pieces of meat. Once the chorizo is brown, approximately 4-5 minutes, drain through a fine mesh strainer and set aside.
Wipe down the pan and add the olive oil. Over medium-low heat, add the onions, garlic, cumin and chili powder. Cook, stirring frequently, until the onions are soft, 3-4 minutes.
Add the diced tomatoes, reserved juice, tomato paste, black beans, spinach, and corn. Continue cooking and stirring until the spinach has wilted, 1-2 minutes, then add the chorizo back to the pot. Remove from the heat and season with salt and pepper to taste.
Place 2 corn tortillas in the bottom of the casserole dish and top evenly with 1/4 of the chorizo filling. Sprinkle 3/4 cup of cheese on top. Repeat this 3 more times, ending with the cheese.
Bake for 20 minutes. Allow to cool for 5 minutes before serving. Use optional toppings if desired.
This freezes very well. Simply divide into individual portions before freezing.Adapted from The Mom 100 Cookbook.