Gather and measure the ingredients for your double chocolate banana bread.
Preheat the oven to 350°F and line a 9 x 15 loaf pan with parchment paper.
In a large mixing bowl, mash the bananas with a fork. Add the egg, butter, yogurt, and vanilla extract, then whisk until fully combined.
Add the white sugar and brown sugar to the banana mixture. Mix until the sugars are fully dissolved.
In a separate bowl, combine the flour, cocoa powder, baking soda, and salt. Mix well, then sift the dry ingredients into the banana mixture and whisk until just combined.
Gently fold the chocolate chips into the batter until evenly distributed.
Pour the batter into the prepared loaf pan and sprinkle additional chocolate chips on top.
Bake for 50 minutes, then insert a toothpick into the center. Continue baking as needed until the toothpick comes out mostly clean with a few moist crumbs.
Let the double chocolate banana bread rest for 20 minutes to firm up before slicing. Enjoy!