Preheat your oven to 350°F (175°C).
In a mixing bowl, combine flour, sugar, cocoa powder, baking powder, and salt.
Add milk, vegetable oil, and vanilla extract to the dry ingredients. Stir until smooth.
Spread the batter evenly in a greased baking dish.
In a separate bowl, mix together sugar, brown sugar, and cocoa powder for the topping.
Sprinkle the topping mixture evenly over the batter.
Pour hot water over the topping. Do not stir.
Bake for 35 minutes or until the center is set.
Let it cool for a few minutes before serving. Enjoy!