Preheat oven to 350°F. In a medium bowl, combine the flour, sugar, 2 tablespoons cocoa, baking powder and salt. Stir in the milk, oil and vanilla until smooth. Spread into an ungreased 9x13 baking pan (may take a bigger pan). Combine brown sugar and remaining cocoa; sprinkle over batter. Pour hot water over all; do not stir. Bake for 35 to 40 minutes. Serve warm. Top with whipped cream or ice cream if desired.
Per Serving: 218 Calories, 4g Total Fat, 1mg Cholesterol, 184mg Sodium, 46g Carbohydrate, 1.5g Fiber, 3g Protein