In a high-wall skillet over medium heat, cook the chorizo and onion for about 15 minutes, until the meat has crumbled completely. (With good chorizo, it will not change color.) Place a stack of paper towel or a lint-free cloth on a plate. Transfer the cooked meat to the plate and allow the oil to drain.
In a high-wall skillet over medium heat, cook the chorizo and onion for about 15 minutes, until the meat has crumbled completely. (With good chorizo, it will not change color.) Place a stack of paper towel or a lint-free cloth on a plate. Transfer the cooked meat to the plate and allow the oil to drain.
Dump the two cans of refried beans into a sauce pan, stirring occasionally, and heat just until smooth. Remove from the heat. (This allows for the refried beans to be used more easily in the next step.)
Use lard or vegetable shortening (lard is preferable) to grease two 13″ x 9″ x 2″ glass casserole dishes. Lay two tortillas in each one. On the tortillas in each dish, spread one-quarter of the refried beans, followed by one-quarter of the meat mixture, one-quarter of the cilantro, and one cup of the shredded cheese. Top each with two more tortillas, and then build a second layer identical to the first. Top with the remaining tortillas and one more cup of cheese each.
Cover each dish with aluminum foil, being sure to “tent” the foil upward in the middle so it isn’t contacting the top layer of cheese.
Bake at 350F for 30 minutes. Let set for 5 minutes before serving. Top each serving with sour cream, more shredded cheese, salsa, or other optional toppings.