Preheat oven to 350 degrees F and grease loaf tin
In a small bowl, peel and mash bananas together well with fork. Mix in cinnamon and milk and set aside
In a medium bowl, cream together butter and sugar until light and fluffy, using hand mixer or fork. Add eggs one at a time, mixing well between each one. Mix in vanilla
Add banana and cinnamon mixture to the butter, sugar, eggs, and vanilla mixture and combine well
Sift together your flour, salt, baking powder, and baking soda in a separate medium bowl, and mix to combine
Add your dry ingredients to your wet mixture, and combine evenly
Combine mocha powder with a small amount of hot water and stir until dissolved, mixing in additional water as needed. Whisk with a fork until the mixture is cooled.
Separate half the banana bread batter into another bowl. Fold in mocha until well combined.
Fill the loaf tin, alternating tablespoon-sized scoops of regular batter and mocha batter to create a checkboard pattern. Continue layering in batter until all batter is gone. Run a butter knife through the batter to swirl together.
Place in oven and bake for 65 - 70 minutes. Remove from oven when a toothpick comes out clean and allow to cool before slicing.