Preheat oven to 350°F (175°C) and grease a loaf pan.
In a large bowl, mash bananas until smooth.
Stir in melted butter, brown sugar, eggs, and vanilla.
In another bowl, whisk flour, baking soda, salt, and cinnamon.
Gradually mix dry ingredients into wet, stirring until just combined.
For the mocha swirl, heat cream in a saucepan until warm.
Remove from heat and stir in chocolate chips, espresso powder, cocoa, and vanilla.
Mix until smooth.
Pour half of the banana batter into the pan.
Drizzle the mocha mixture over it.
Add the remaining banana batter and swirl lightly with a knife.
Bake for 50-55 minutes or until a toothpick comes out clean.
Let cool before slicing—if you have the patience.