Preheat oven at 180°
Grease the baking tray with butter or oil
Mix sugar, butter and oil and whisk until well combined
Add milk and vanilla extract and whisk well till sugar starts melting
At this stage add flour, cocoa powder, baking powder and salt and whisk the batter
Batter should be of thick consistency
Transfer the batter in the baking tray and bake it for 20-25 minutes
Cover with cling paper and refrigerate for 2 hrs