01 - Preheat oven to 350°F. Grease a 9x5-inch loaf pan with nonstick spray.
02 - In a large bowl, whisk together all-purpose flour, baking soda, and salt until evenly combined.
03 - In a separate bowl, mash bananas thoroughly. Add granulated sugar, brown sugar, melted unsalted butter, eggs, and vanilla extract. Whisk until smooth with minimal lumps.
04 - Fold the dry ingredients into the banana mixture gently, just until no streaks of flour remain. Do not overmix.
05 - Carefully fold in fresh raspberries, distributing them evenly throughout the batter.
06 - Pour half the batter into the prepared pan. Drizzle melted chocolate over the batter, then top with remaining batter. Use a butter knife to gently swirl the chocolate through the loaf.
07 - Transfer the loaf pan to the center rack in the oven and bake for 55 to 65 minutes, or until a toothpick inserted in the center comes out clean.
08 - Allow bread to cool in the pan for 15 minutes before transferring to a wire rack. Slice and serve once fully cooled.