Preheat oven to 350°F (175°C). Grease or line a 9×5 inch loaf pan.
In a bowl, whisk together flour, baking soda, salt, and cinnamon.
In a large bowl, whisk sugars and eggs until smooth. Stir in buttermilk (or yogurt), vanilla, mashed bananas, and olive oil.
Gently fold dry mixture into wet mixture until just combined (don't overmix).
Divide batter into two bowls and mix 3 tablespoons of black sesame paste into one bowl.
Pour batter into pan alternating between regular and black sesame batter. Bake 55–65 minutes, until a toothpick comes out clean.
Let rest in pan 10 minutes, then transfer to a wire rack to cool.
