Preheat the oven to 375@. In a large bowl mix together the biscuit mix and cocoa, then stir in 1 cup sweetened condensed milk, 1/4 cup chocolate syrup and the vanilla extract; blend well. Spoon the mixture evenly into a greased 8" square baking pan. In a small bowl combine the remaining milk and syrup with the water. Pour the liquid mixture over the cake mixture. Do not stir. Bake for 30 to 35 mins or til the center is set and the cake begins to pull away from sides of pan. Remove from the oven and let stand for 15 mins. Spoon into dessert dishes, spooning pudding from the bottom of the pan over the top. Note: Serve warm with whipped cream, whipped topping or ice cream. Refrigerate leftovers if there are any.