Preheat oven to 400 degrees.
Add the beef to a skillet over medium heat and brown. If there is a lot of grease in the pan, drain it before going on to the next step.
Add the onions to the beef and cook until soft (about 3-5 minutes).
Add the green chilies, salt, pepper and cumin and cook for 1 minute.
Add enchilada sauce and simmer for 10 minutes.
Add the Velveeta to the beef mixture and continue heating until it is fully melted. Mixture should be thick and cheesy when done.
Grease the cast iron skillet with shortening, lard, or non-stick spray.
Spread one quarter of the chilled masa on the bottom of the pan.
Add the beef mixture.
Spread the remaining masa dough on top (see notes if having difficulty)
Bake for 35-45 minutes, or until the masa is golden brown. Let rest for 5-10 minutes before serving