Preheat your oven to 350°F (175°C) for even baking.
Grease your loaf pan with butter or non-stick spray and set aside.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, mash the ripe bananas until smooth. Add the eggs, granulated sugar, brown sugar, vanilla extract, and melted butter. Whisk until well combined.
Gradually add the dry mixture to the wet ingredients, stirring gently with a rubber spatula until just combined.
In a small bowl, combine the black sesame tahini and black sesame powder, stirring until smooth.
Spoon half of the banana bread batter into the prepared loaf pan. Dollop half of the black sesame mixture on top and swirl gently. Repeat with remaining batter and black sesame mixture.
Sprinkle granulated sugar on top for a sweet crust. Bake for 55-65 minutes, or until a toothpick inserted in the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a cooling rack to cool completely before slicing.
