01 - Preheat oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper.
02 - Whisk together flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
03 - In a large bowl, combine mashed bananas, granulated sugar, brown sugar, and melted butter until well incorporated.
04 - Beat in eggs, espresso, and vanilla extract until mixture is smooth and uniform.
05 - Gently fold dry ingredients into wet mixture until just combined. Avoid overmixing to prevent tough texture.
06 - Fold in chocolate chips or chopped chocolate until evenly distributed throughout batter.
07 - Pour batter into prepared loaf pan. Smooth top surface and sprinkle with additional chocolate chips if desired.
08 - Bake for 50-55 minutes until toothpick inserted into center emerges clean or with few moist crumbs.
09 - Cool in pan for 10 minutes. Transfer to wire rack and let cool completely before slicing.