01 -
Preheat the oven to 350°F (175°C). Grease and flour an 8.5 by 4.5-inch loaf pan or line it with parchment paper overhanging all sides for easy removal.
02 -
In a medium bowl, whisk together mashed banana, buttermilk, oil, egg, vanilla extract, and brown sugar until thoroughly combined.
03 -
In a large bowl, whisk flour, cocoa powder, baking soda, salt, and optional espresso powder until evenly blended.
04 -
Pour wet ingredients into dry ingredients and stir gently until just combined to avoid overmixing. Fold in 3/4 cup of chocolate chips.
05 -
Evenly pour the batter into the prepared loaf pan and level the surface with a spatula.
06 -
Bake for 65 to 75 minutes, or until a toothpick inserted in the center comes out clean.
07 -
Immediately after removing from the oven, sprinkle the remaining 1/4 cup of chocolate chips on top to melt into the crust.
08 -
Allow the loaf to cool completely in the pan before slicing and serving.