Pour some water (1"-2" deep) at the bottom of your steaming pot, place the steamer insert on top (make sure the water line is not above the insert) and bring to a simmer over medium heat on the range top. See notes if you don't have a steaming pot.
For the tamal batter:
In a large tub, beat the shortening until soft. It is easier if you do it by hand. Start adding the Masa harina gradually, along with the baking powder, the canned milks, the water, lime zest and half a sleeve of crushed Maria cookies. See notes if you like your tamales sweeter.
Make the filling:
In a large bowl, beat the cream cheese with the half cup of sweetened condensed milk and the lemon juice until fully integrated. Add the remaining crushed Maria cookies and mix well.
Assemble the tamales:
Take a tamal husk in your palm with the straight edge facing toward your fingertips. Spread in the center, about 2" from the bottom of the husk (pointing toward your wrist) a portion of tamal batter first and then, on top and center of the batter spoon some of the filling. Carefully wrap your tamal so that neither batter nor filling leak out of the husk. Fold in the husk sides first, then fold in the pointy tip. Wrap each tamal tightly enough so that the filling doesn't leak out, but not too tight either, because it will also cause the filling to spill out. If a husk tears or breaks or is not wide enough, simply overlap another one on top. Repeat with the remaining 13 husks and carefully place the tamales standing, straight and open edge up, inside the steamer. Make sure that all the tamales stand straight, with the opening side up. Also check that the water at the bottom doesn't go above the insert or gets into the tamales.
Steam for at least 1 hour and 30 minutes. If you hear a crackling noise coming from the steaming pot it means all or most of the water has evaporated. Add more water if needed, very carefully so that none of it gets into the tamales when you pour it. The tamales will look tender at first but they will be fully cooked after the steaming time.
Garnish with thin slices of lime and drizzle with sweetened condensed milk when serving. Enjoy!