Preheat oven to 350*.
Combine flour, sugar, 2 TBL cocoa, baking powder, and salt.
Stir in the milk, oil, and vanilla til smooth.
Spread in ungreased 9x9 pan.
Combine brown sugar and remaining cocoa; sprinkle over batter.
Pour hot water over all; do not stir.
Bake at 350* for 35-40 minutes.
Serve warm with ice cream or whipped cream.