Preheat oven to 170 degree C.  Line a loaf pan with parchment paper, grease with oil and set aside.

Take chocolate in a bowl and melt it gently. add cocoa and mix well.

Take flour, baking soda and salt.

Take butter, sugar and vanilla and beat till fluffy.

Add in eggs and beat till creamy. Add banana puree, curd and beat again.

Add in flour and fold gently. Once it is combined, divide it into two bowl.

To one bowl, add in chocolate and fold gently.

Now take the loaf pan, spoon  banana batter and then chocolate batter. Spread evenly and bake for 1 hour and 15 mins.

Insert a toothpick to check whether the cake is done, if it comes out clean then it is done.

Remove it from oven, cool it down for 15 mins.

Invert it on a cooling rack and let it cool completely.

Slice and serve.

Spoon the plain batter and chocolate batter alternately into the prepared loaf pan. Swirl the batters together with a knife (don't overdo it or the colors will get muddled -- up and back 4-5 times should suffice). Now bake.