Preheat oven to 350°F. Grease a loaf pan and line with parchment paper. For a taller loaf, use an 8 ½ by 4 ½ inch pan. For a wider loaf, use a 9x5 inch pan.
On medium speed of an electric mixer, beat together mashed bananas, yogurt, tahini, melted butter, vanilla and eggs. Add sugars; beat until just combined.
Whisk together the flour, baking soda, and salt , then stir into the banana mixture until evenly blended. Fold in chocolate.
Pour batter into prepared pan and sprinkle top with sesame seeds or nuts.
Bake at 350°F for 55 to 70 minutes or until a skewer inserted comes out clean. Let cool completely, then remove from pan. The 55 minute time is if you are using a 9x5 inch loaf pan (wider). If using a narrower loaf pan like an 8 ½ by 4 ½, the bread will take longer. To be sure it's done, you can measure temperature with a meat thermometer. It should be at least 205 degrees F.