In a medium bowl, combine the flour (sifted), cocoa (sifted), baking powder and salt. Mix and set aside.
In a large bowl, beat the eggs well. Add the sugar gradually and mix in the oil and vanilla.
Add the dry ingredients to the wet ingredients and mix well. A spoon or spatula will do the trick.
Lightly spray a 9x13in (33 x 23cm) pan with oil and pour batter in. Option to sprinkle a handful of chocolate chips on the top before baking. Bake for 20 - 30 minutes or until a toothpick inserted in the center of the brownies comes out clean.
Notes
Use a little less flour and ½ tsp of baking powder for more fudgier brownies.