Place the prepared masa in a large bowl and add the chopped peppers, shredded cheese, corn kernels and 1½ tablespoons sugar.
Mix with your hands to integrate all ingredients.
Add the ½ cup milk gradually if mixture is too dense to spread easily. Mix until the masa is spreadable.
Assemble Tamales
Spread about ¼ cup masa mixture onto the the corn husk, filling it up to 2 inches from the bottom and ¼ inch from the top. Divide dough evenly, spreading onto 12 large corn husks or 24 smaller ones.
Fold sides of husk together, 1 over the other. Fold the bottom of the husk over the seam of the 2 folded sides. Repeat with remaining husks.
Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil. Add tamales with the open side up.
Steam for one and a half hour on medium heat.
When tamales are ready, they should still be very moist but pull away from the corn husk easily and hold together.
Let tamales rest for 15 minutes before serving.
Notes
For the roasted chiles, it's okay to substitute with canned roasted green chile.