Boil the milk and add the chocolate. Stir constantly until chocolate is completely melted. Add the butter and the sugar. Mix until smooth. Set aside to cool.
Mix in the corn flour and baking powder together in a bowl. Slowly add the hot liquid and mix by hand for 10 minutes. Grease 2 dozen muffin pans and line with corn husks. Fill with tamal mixture and bake for 20 minutes.