01 - Preheat the oven to 350°F and line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - In a large bowl, mash the bananas until smooth. Whisk in eggs, Greek yogurt, honey, oil, and vanilla extract until well combined and creamy.
03 - In a separate medium bowl, whisk together the whole wheat flour, baking soda, baking powder, cinnamon, and salt until evenly distributed.
04 - Gradually add the dry ingredients to the banana mixture, stirring gently with a spatula until just combined. Do not overmix—some small lumps are fine.
05 - Gently fold in the chopped walnuts or pecans and dark chocolate chips if using, distributing evenly throughout the batter.
06 - Divide the batter evenly among the prepared muffin cups, filling each about 3/4 full.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center of a muffin comes out clean and tops are golden brown.
08 - Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before storing.