Heat the oven to 350 degrees F. Place paper liners in a standard muffin tin or grease the tin with oil spray.
In a medium bowl, whisk the flour, cocoa powder, baking powder, baking soda, and salt, breaking up any clumps of cocoa powder.
In a large bowl, whisk the mashed banana, eggs, oil, maple syrup, yogurt, and vanilla.
Add the dry ingredients and 1/2 cup of the chocolate chips to the we ingredients and mix until just combined.
Fill each muffin cup all the way to the top then place a few additional chocolate chips on top of each muffin.
Bake until the center of each muffin no longer looks wet or a cake tester inserted into the center of a muffin comes out with a few moist crumbs, 15 to 20 minutes.
Allow muffins to cool then enjoy. Store muffins in an air tight container at room temp for 1 day then in the fridge for 4 days. Muffins can be individually wrapped and frozen for a month.