Add bananas to a large mixing bowl and mash with a fork or potato masher.
Add melted butter, egg, vanilla extract and greek yogurt.
Mix until the mixture is well combined.
Add the sugars and stir until dissolved.
Add the flour, cocoa powder, kosher salt, baking soda, and mix until just combined.
Fold in chocolate chips until combined.
Pour the batter into the prepared loaf pan and top the batter with extra chocolate chips.
Bake for 50-60 minutes until a toothpick inserted into the banana bread comes out clean. Let the banana bread cool for at least 20 minutes before removing from the pan.