Pre heat oven to 220°. Mix butter and sugar until its fluffy

Add vanilla essence and mix a little bit

Add one egg at a time and mix that well too.

Incorporate your flour and milk to the mixture until combined but don't over do it.

Divide your batter into two and mix your cocoa into one of the batter until its well combined.

Pour your batter in the baking tin as desired.

Bake for 45min