Line a 9×5 inch loaf pan with parchment paper and preheat the oven to 350F.
Add the bananas to a large mixing bowl and using a fork, mixer, or whisk, mash the bananas until pureed.
Add the sugar, yogurt, oil and vanilla to the bowl with the mashed bananas and whisk until thoroughly combined.
Add in the baking soda, flour, and salt and use a spatula to fold the dry ingredients into the wet ingredients, being careful not to over mix.
Divide the batter evenly into two bowls. To one of the bowls add the cocoa powder and chocolate chips. Using a spatula, fold until just combined.
Alternate adding scoops of the batter into the loaf pan. Start with the chocolate batter, followed by the regular batter, and so on. Continue doing so until all the batter is used up.
Bake for 55-65 minutes, or until golden brown and cooked thoroughly.
Let cool for 20 minutes in the pan, and then remove and let the bread finish cooling on a rack. P.S. Make sure not to cut into it immediately or else it can get mushy!