Preheat the oven to 350°F (175°C) and grease a loaf pan.
Mash bananas in a bowl until smooth.
Stir in melted butter, brown sugar, eggs, and vanilla.
Whisk together flour, baking soda, salt, and cinnamon in a separate bowl.
Fold in the dry ingredients until just combined.
For the mocha infusion, heat heavy cream in a saucepan until warm.
Remove from heat and stir in chocolate chips, espresso powder, cocoa, and vanilla.
Stir half of the walnuts into the banana batter.
Pour the batter into the prepared loaf pan.
Drizzle the mocha mixture over the top and swirl it gently with a toothpick.
Sprinkle the remaining walnuts on top for extra crunch.
Bake for 50-55 minutes until a toothpick inserted in the center comes out clean.
Cool for at least 15 minutes before slicing—if you