Use a sharp knife to cut the husks off 2 ears of sweet corn right where the kernels begin. Put the husks in a plastic bag and refrigerate. Discard the corn silk.
Cut the kernels off the cob and place in a food processor. Process to make a coarse puree.
Mix 1 3/4 C. masa for tamales with 1 C. plus 2 T. hot water, then allow to cool.
Add the masa to the sweet corn along with 1 stick of unsalted butter cut into small cubes, 1/2 t. salt, and 1 1/2 t. baking powder. Pulse several times, then let the processor run for 1 minute. The mixture should be light and fluffy.
Separate the corn husks into individual leaves. Line a steamer with the smallest leaves.
To assemble the tamales, fill the larger leaves with 3 T. dough. You can add Jack or Cheddar cheese, roasted peppers (hot or sweet), sauteed onions or other savory ingredients.
Place the tamales in a single layer in the steamer, then cover with any leftover corn husk leaves. Steam for 1 hour or more, until the tamales easily come free from the husks.