Hot Fudge Pudding Cake

I'm at my parents' place in Florida, leafing through my mom's cookbooks. I came across a recipe that I can't wait to make. I just ate something like this on our cruise for dessert.

1 1/4 cup sugar, divided
1 cup all-purpose flour
1/2 cup cocoa powder, divided
2 tsp baking powder
1/4 tsp salt
1/2 cup milk
1/3 cup butter, melted
1 1/2 tsp vanilla
1/2 cup packed brown sugar
1 1/4 cups hot water
Whipped topping

Heat oven to 350. Stir together 3/4 cup sugar, flour, 1/4 cup cocoa, baking powder and salt. Stir in milk, butter and vanilla; beat until smooth. Pour ungreased 9-inch square baking pan. Stir together remaining 1/2 cup sugar, brown sugar and remaining 1/4 cup cocoa; sprinkle mixture evenly over batter. Pour hot water over top. Do not stir.

Bake 35 to 40 minutes or until center is almost set. Let stand 15 minutes; spoon into dessert dishes, spooning sauce from the bottom of the pan over the top. Garnish with whipped topping.