Prep the pan and oven: Heat the oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment and lightly grease it so the bread lifts out easily.
Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth with a few small lumps.
You should have about 1 1/2 cups.
Whisk in the wet ingredients: Add the eggs, granulated sugar, brown sugar, oil, and vanilla. Whisk until the mixture looks smooth and glossy.
Combine the dry ingredients: In a separate bowl, whisk the flour, cocoa powder, baking soda, baking powder, and salt. This helps prevent cocoa clumps.
Bring it together: Add the dry ingredients to the banana mixture.
Stir gently with a spatula until just combined. Do not overmix—a few streaks of flour are fine.
Fold in the chocolate: Gently fold in the chocolate chips (and nuts if using). Sprinkle a few extra chips on top for a bakery-style look.
Bake: Pour the batter into the prepared pan and smooth the top. Bake for 55–65 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs.
Cool: Let the loaf cool in the pan for 10–15 minutes, then lift it out and cool completely on a wire rack.
Slicing while warm can make it crumbly, so give it time to set.
Slice and enjoy: Use a serrated knife for clean slices. Serve plain, or with a smear of peanut butter for extra indulgence.