no boxed mix here.
1 1/3 cups flour
2 cups sugar
3/4 cup cocoa powder
1 tsp baking powder
1/2 tsp salt
2/3 cup vegetable oil
3 eggs
2 tsp vanilla
Coat a 13x9 pan with baking spray. Whisk together flour, sugar, salt, cocoa, baking powder, and salt. In another bowl, combine oil, eggs, and vanilla; add to dry ingredients and mix until just combined.
Bake at 350° for 28 minutes or until centers are dry.