Preheat the oven to 350°F and grease a 9×5-inch loaf pan; line with parchment with 1-inch overhang for easy removal.

In a medium bowl mash the bananas until mostly smooth, then stir in the melted butter, eggs, and vanilla until combined.

Whisk together 2 cups all-purpose flour, 1/3 cup whole wheat flour, baking soda, baking powder, salt, and cinnamon in a large bowl.

Stir the granulated and brown sugars into the banana mixture until blended, then fold the dry ingredients into the wet mixture just until no large streaks of flour remain; batter should be thick and scoopable.

Toss raspberries and chopped dark chocolate with the reserved 1 tablespoon flour, then gently fold into the batter until evenly distributed; transfer batter to the prepared pan and smooth the top, adding a few chocolate pieces and berries on top if desired.

Bake at 350°F for 55–70 minutes until a toothpick shows a few moist crumbs or an instant-read thermometer registers about 200°F in the center; tent with foil if the top browns too quickly, then cool in the pan 15 minutes before lifting out and cooling completely on a rack.