In a bowl add butter and sugar and mix till light and fluffy.

Add eggs one after the other and mix well till the yellow is not seen anymore.

Sift in flour and baking powder and mix well,then add vanilla flavor and mix till well combined.

Divide the mixture into two and add the cocoa powder in one of the parts and mix.

Grease your baking pan and add the mixture,the vanilla mixture first then chocolate mixture, then use some clean stick or toothpick to spread it.

Bake and allow to cool then serve.