Preheat the oven to 180°C /356°F.
Grease and line the loaf tin with baking paper/parchment paper.
In a bowl, mash the bananas with the help of a fork and keep aside.
Take a bowl, sift plain flour, cocoa powder and baking soda. Keep aside.
In a banana mixture, add melted unsalted butter, brown sugar and whisk nicely until everything is combined.
Then add egg and combine well.
Next add the sifted flour, baking soda, cocoa powder along vanilla extract, cinnamon powder and mix well without any lumps.
After that add chocolate chunks and stir well.
Transfer the batter into the greased loaf tin, add chocolate chips and bake for 50-60 minutes or until the skewer comes clean (here mine done exactly 55 mins)
Allow it to cool in the tin for 10-15 mins and then transfer it on a wire rack to cool completely.
After that slice the cake and enjoy!