Preheat the oven to 350 degrees F. Spray a muffin pan with cooking spray.
In a medium bowl, mash the bananas.
Add the maple syrup, vanilla, eggs, oil, and Greek yogurt.
In a smaller bowl, whisk together the flour, cocoa powder, baking soda, and salt.
Add the flour mixture to the wet ingredients and stir until just combined.
Fold in the chocolate chips.
Divide the batter between the 12 muffin cups.
Bake in the preheated oven for 18-20 minutes, until baked through.
Enjoy!
Store leftovers in an airtight container.