Preheat oven 180 degrees. Grease and flour a 9 inch cake pan and set aside.

Whisk together flour, baking powder and salt and set aside.

Break eggs into a bowl and beat using an electric beater along with the sugar till fluffy and pale, around 5 minutes.

Add in the milk, oil and vanilla and beat till combined.

Add the dry ingredients and just beat till combined, do not overbeat.

Divide the batter into two. Add the cocoa powder into one bowl and fold in till done.

Into the prepared pan, pour three tablespoons of the plain batter into the center. Now pour three tablespoons of the chocolate batter into the center. You will see the batter taking a round shape.

Continue to pour the batter intermittently without stopping till the batter looks like a "zebra". Do not tap or shake the pan under any cost.

Slide the pan into the oven carefully and bake for 30-40 minutes or until skewer comes out clean.

Cool in the pan for 5 minutes before flipping onto a cooling rack. Cool completely, slice and serve!