Torta de ChocolateChocolate is one of Mexico's food gifts to the world. I used Mexican chocolate to develop this cake; I prefer Mayordomo or Guelaguetza brands from Oaxaca, which are not available in the United States, but Ibarra or Abuelita brands are widely available in our markets and they are fine for the cake. (See Mail-Order Sources for Ingredients for Mayordomo or better yet, go to Oaxaca!)