Popular american desert for everyone who loves taste of cocoa.
Preheat the oven to 350 °F (175 °C). In a large bowl, stir together the flour, sugar, cocoa powder, baking powder and salt. Pour in the water, vegetable oil and vanilla; mix until well blended. Spread evenly in a 9 x 13 inch baking pan. Bake for 25 to 30 minutes in the preheated oven, until the top is no longer shiny. Let cool for at least 10 minutes before cutting into squares.