Sift flour, baking powder, soda, powdered sugar, cocoa powder in a bowl, mix it well and keep aside.
In another bowl add condense milk, vanilla essence, water, mix it well.
Now gradually add dry mixture into the bowl of condense milk mixture and mix it well.
Add melted butter, oil in the batter and mix it well in cut and fold method to trap the air which makes the cake soft and spongy.
Lastly add vinegar, mix it well and make smooth batter.
Divide the batter into two equal parts.
Take one part of the batter, pour cocoa powder, few drops of colour and mix it well.
This way vanilla batter and colourful batter are ready.
To make zebra cake pour both the batter separately into the pipping bag and keep aside.
10. Take 6 inch aluminium tin, grease it with butter and dust with flour.
11. Pour 1 tbsp of plain/ vanilla batter in the middle of the prepared pan and then pour over 1 tbsp of colourful batter. Repeat the process and use both the batters alternate to make layers until all the batter has been used.
12. Tab the pan on countertop so that air bubbles gets removed and bake it on 180 degree in a pre-heated oven for 40 minutes or till the knife inserted into the center of cake comes out clean.
13. Once baked, Keep the cake cool down for sometime.
14. Once it cools down a bit, scratch the sides of the pan, invert the tin and tap sharply to unmould the cake.