Marble banana bread

Hi there!
I've been up to experimenting new recipes in the last few days and here is one of the amazing results: a moist and fluffy marble banana bread.
INGREDIENTS:
1 beaten egg
3 ripe bananas mashed
1.5 cups of self rising flour
2/3 cup of granulated sugar
1/2 cup of milk
1/2 cup of vegetable oil
1 table spoon of cocoa powder
a bit of vanilla powder
a touch of salt
PROCEDURE:
Preheat the oven to 375 F.
Beat the egg, mash the bananas, mix together with vanilla powder, salt, sugar. Add the self-rising flour, milk and oil while stiring. Pour half of the mixture into a bread pan covered with cooking parchment. Finally add cocoa powder to the remaining mixture, blend it and pour into the bread pan.
To give an artistic touch to your banana bread use a fork to "draw" waves of cocoa mixture on the plain one (see top picture for a naive example).
Enjoy!

PS. As you could see from top picture if you are running out of bread pan you can use a different shape.