Prep the pan and oven: Heat oven to 350°F (175°C).
Line a 9x5-inch loaf pan with parchment, leaving a little overhang for easy lifting. Lightly grease.
Mash bananas: In a large bowl, mash bananas until mostly smooth with some small bits left for texture.
Whisk wet ingredients: Add eggs, maple syrup (or honey), oil, vanilla, and Greek yogurt. Whisk until combined and creamy.
Combine dry ingredients: In a separate bowl, whisk white whole wheat flour, all-purpose flour, cocoa powder, baking soda, baking powder, salt, and cinnamon.
Mix batter gently: Add dry ingredients to wet.
Stir with a spatula just until no dry streaks remain. Do not overmix.
Fold in chips: Gently fold in the chocolate chips, reserving a tablespoon to sprinkle on top.
Fill the pan: Scrape batter into the prepared pan, smoothing the top. Sprinkle remaining chips over the surface for a bakery look.
Bake: Bake 50–60 minutes, or until a toothpick inserted near the center comes out mostly clean with a few moist crumbs.
If the top browns too quickly, tent with foil during the last 10–15 minutes.
Cool: Let the loaf cool in the pan for 10–15 minutes, then lift out using the parchment and transfer to a wire rack. Cool completely before slicing for best texture.
Slice and enjoy: Use a serrated knife for clean slices. Serve slightly warm or at room temp.