1. Heat oven to 325°F. Heat sugar in heavy medium skillet or saucepan over medium low heat, stirring occasionally, until melted and golden brown. Pour into bottom of 1-1/2 quart baking dish.
2. Pour evaporated milk into 2-cup glass measuring cup; add water to make 1-1/4 cups. Place cocoa in medium bowl; add enough of the reconstituted milk to form a paste and then gradually blend in the remaining milk.
3. Place chocolate milk mixture, sweetened condensed milk, eggs, vanilla and salt in blender container. Cover; blend until smooth and well blended. Gradually pour over sugar mixture in baking dish. Cover top of baking dish with foil to keep it from browning.
4. Set dish in a larger baking pan. Fill the larger pan with water until it reaches halfway up sides of dish. Bake 1-1/2 to 2 hours or until knife comes out almost clean when inserted halfway into center of custard. (Do not pierce bottom.) Remove from water to wire rack. Cool 2 hours. Cover; refrigerate overnight or until thoroughly chilled (about 8 hours).
5. To serve, run a knife or rubber scraper along the outside of the flan. Place serving plate over baking dish; invert onto serving plate. Let stand several minutes for the flan to release and the topping to drip down; remove baking dish. Garnish as desired. 8 to 10 servings.
* 1-1/4 cups whole milk may be substituted for the reconstituted evaporated milk.