Preheat oven to 350 degrees F or 175 C degree for 10 minutes.
Grease a 9 inch round cake pan with 1tsp oil.
Take a mixing bowl, combine flour ,baking powder, and baking soda...mix well and set aside.
Take a another bowl ,add butter and sugar..mix until creamy...add eggs(if you use condensed milk. .then add condensed milk) ..Add vanilla essence and milk...mix until a creamy texture.
Add flour mixture into this creamy mixture slowly...mix until smooth.
Reserve 1/2 cup batter; pour the remainder white batter into the greased pan.
Stir cocoa into the 1/2 cup reserved batter and mix well using a fork.
Drop by spoonfuls over top of white batter.
Using a knife, swirl the cocoa batter into the white batter to incorporate it in a marble effect.
Bake in preheated oven for 30 to 35 minutes, or Insert a toothpick to check. .if the inserted toothpick comes out clean then it is done
Remove from oven and let cool for 10 minutes..cut into slices..then serve and enjoy.
