01 - Preheat oven to 350°F. Line a 9 x 5 inch loaf pan with parchment paper or grease lightly.
02 - In a large mixing bowl, whisk together mashed bananas, eggs, vegetable oil, brown sugar, and vanilla extract until smooth and well combined.
03 - In a separate bowl, sift together flour, cocoa powder, baking soda, and salt to remove lumps and evenly distribute leavening agents.
04 - Gradually fold dry ingredients into wet mixture using a spatula until just combined. Do not overmix to maintain tender crumb structure.
05 - Gently fold in chocolate chips and walnuts if using, distributing evenly throughout batter.
06 - Pour batter into prepared loaf pan and smooth the top surface with a spatula.
07 - Bake for 50 to 55 minutes, or until a toothpick inserted into the center emerges with a few moist crumbs.
08 - Allow bread to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.