Preheat oven to 350 degrees.
In a mixing bowl sift together the flour, sugar, 2 tbsp cocoa, baking powder, and salt.
Blend in the milk and melted shortening.
Spread evenly in an ungreased 9" x 9" casserole or pan.
Combine the brown sugar with 1/4 cup cocoa. Sprinkle over the batter.
Pour hot water over batter.
Bake for 45 minutes.
Cut into squares while hot and invert onto a plate. Top with sauce.