The corn and husks. With a large knife, cut through the ears of corn just above where cob joins stalk. Carefully remove the husks without tearing, wrap in plastic and set aside. Pull off the corn silk and discard. Slice off the corn kernels and place in the bowl of a food processor. Scrape the cobs with the end of a spoon to remove all the little bits of remaining corn and add to the food processor. Process the corn to a medium-coarse puree.
The dough. Add the fresh or reconstituted masa to the corn, along with the butter, lard, sugar, salt and baking powder. Pulse the processor several times, then let it run for 1 minute, until the mixture is light and homogeneous.
Setting up the steamer. Set up a small steamer by placing a collapsible vegetable steamer into a large deep saucepan. Line the steamer with the smallest husks to protect the tamales from direct contact with the steam and to add more flavor. Make sure to leave tiny spaces between the husks so condensing steam can drain off. Pour an inch or so of water into the bottom of the steamer and heat to a boil. Lower the heat to medium.
Forming and steaming the tamales. First, tear extra husks into twelve ¼-inch-wide, 7-inch long strips. Then use the dough to form 12 unfilled tamales by spreading ¼ cup of the dough into about a 4-inch square, leaving at least a 1½-inch border on the side toward you and a ¾-inch border along the other sides (with large husks, the borders will be much bigger.) Pick up the two long sides of the husk and bring them together. If the uncovered borders of the two long sides you’re holding are narrow, then tuck one side under the other; if wide, then roll both sides in the same direction around the tamal. If the husk is small, wrap the tamal in a second husk. Finally, fold up the empty 1½-inch section of the husk (to form a tightly closed “bottom” leaving the top open), then secure it in place by loosely tying one of the strips of husk around the tamal. As they’re made, stand the tamales on its folded bottom in the prepared steamer. Don’t tie the tamales too tightly or pack them too closely in the steamer; they need room to expand. However, if your tamales don’t take up the entire steamer, fill in the open spaces with loosely wadded aluminum foil to keep the tamales from falling over. Top with additional husks, cover and steam for 1 to 1 ½ hours, until the tamales come free from the husks. Watch carefully to make sure that all the water doesn’t boil away and to keep the steam steady. If more water is necessary, pour boiling water into the pot.