In each of two large stockpots, combine 2 cups cocoa, 1 cups sugar, and 1 teaspoon salt. Gradually stir 5 cups water into each pot. Bring to a boil; reduce heat. Whisk in milk, cream, and remaining water; heat through. Remove from heat; stir in vanilla. Garnish with whipped cream and additional cocoa.
Yield: 65 (1-cup) servings