SORT corn husks, setting aside any torn ones. Place intact husks in large bowl. Cover husks with warm water; soak for at least 1 hour or until softened and easy to fold. (A plate placed on top of husks will help in keeping husks submerged.)
PLACE corn, evaporated milk, queso fresco, media crema, sugar, and salt in blender container. (This may need to be done in batches.) Blend until smooth. Transfer mixture to large bowl. Add baking powder. Gradually stir in corn masa, mixing until consistency of thick cake batter (masa).
JOIN 2 husks by overlapping wide ends of each. Spread 1/4 cup masa, using back of a spoon, to form a square in the center of the husks. Fold right then left edge of husks over masa. Fold up bottom edge, then top edge. Tie with strip of corn husk if desired. Repeat with remaining ingredients. (Note: pending size of husk, 1 husk may be large enough to fold.)
PLACE vegetable steamer in pot with lid; add water to just below steamer. Arrange tamales upright in steamer rack. Cover top of tamales with reserved dry husks and a damp towel; cover. Bring to a boil; reduce heat to low. Steam, adding water as needed, for about 2 1/2 to 3 hours or until masa pulls away from husks (there may be some slight sticking). This will be a soft filling that will firm up on cooling and before serving. Tamales may be frozen and reheated.