In a large bowl, mix together ¾ cup sugar, flour, ¼ cup cocoa, baking powder and salt.
Add in the milk, butter, and vanilla and stir until smooth.
Pour batter into an ungreased 9 x 9 inch square baking pan.
Stir together remaining ½ cup sugar, brown sugar and remaining 1/4 cup cocoa; sprinkle mixture evenly over batter.
Pour hot water over top; do not stir (I know that it sounds weird, but I promise that it will all work out!).
Bake 35 to 40 minutes or until center is almost set (you do not want to over cook or it will not have the warm gooey pudding in the bottom).
Remove cake from oven and let cool for about 15 minutes. When you scoop the cake into serving dishes, be sure to spoon the sauce from the bottom of the pan over the cake. Top with ice cream and hot fudge if desired.
Notes
You can also garnish with fresh fruit like raspberries or strawberries, or chopped nuts are delicious on this too!