Add and stir together the flour, baking powder, salt, 3 tablespoons of the cocoa, and 3/4 cup of the white sugar. Reserve the remaining cocoa and sugar for the pudding.
Add the milk, melted butter, and vanilla to the flour mixture and mix until smooth. Pour into an ungreased 8-inch baking dish.
In another separate small bowl, mix the remaining 1/2 cup white sugar, brown sugar, and remaining 4 tablespoons of cocoa and sprinkle this mixture evenly over the cake batter.
Pour the hot tap water over all. BUT...DO NOT STIR!
Bake @ 350 degrees for about 40 minutes or until the center is set.
Let stand for a few minutes.
Serve with homemade ice cream using the gooey sauce to spoon over all.