Preheat the Oven: Preheat the oven to 350°F (175°C) and grease a loaf pan.
Mix Dry Ingredients: In a bowl, whisk together flour, baking soda, and salt.
Mash Bananas: Mash the bananas with a fork in a separate bowl.
Combine Wet Ingredients: Add melted butter, sugar, eggs, and vanilla to the mashed bananas.
Add Dry Ingredients: Slowly mix in the dry ingredients, then stir in the sour cream and walnuts.
Bake the Bread: Pour the batter into the loaf pan and bake for 60 minutes, or until a toothpick comes out clean.
Make the Espresso Syrup Glaze: Combine brewed espresso, brown sugar, butter, and vanilla in a saucepan and simmer for 5 minutes.
Drizzle the Syrup: Once the bread cools, drizzle the espresso syrup over the top.
Serve: Let the syrup set, slice, and enjoy!