Preheat oven 350 F
Mix in a bowl: 1/4 c flour, half of 1/3 c cocoa powder, 1/8 tsp baking powder and a pinch of salt
In a separate bowl, mix: 1/4 c oil, 1/2 c sugar, 1 tsp vanilla essence, and 1 egg, with wire whisk
Add in flour mixture into egg mixture, stir to combine and pour into a square mold
Bake for 25 mins and let cool completely at room temperature before adding filling