Preheat the oven at 170 C ten minutes before you start baking.
Brush the cake pan with oil and dust it with cocoa powder.
Sieve flour, baking powder, soda and cinnamon in a bowl. Mix well
In a separate bowl, whisk in oil and sugar.
Crack an egg and mix well.
Blend the banana to form a puree. Add this to oil and sugar. Mix well.
Now add flour in batches and mix lightly till everything incorporates. Don't over mix.
Divide the batter into two. Melt chocolate and Nutella in microwave.
Mix half the batter in chocolate mixture.
Then in the prepared cake pan, add a layer of chocolate batter followed by plain banana batter. Make 4 layers of the same.
Take a knife and twirl it around 4 or 5 times. Do not overdo or you'll end up mixing everything.
Bake for approx 35 mins or till toothpick inserted at the centre comes out clean.
