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 thoroughly combined.
03 - In a separate medium bowl, whisk together the whole wheat flour, baking soda, baking powder, cinnamon, and salt until well blended.
04 - Gradually add the dry ingredients to the banana mixture, folding gently with a spatula until just combined. Do not overmix as this will result in dense muffins.
05 - Gently fold in the chopped walnuts or pecans along with the optional dark chocolate chips until evenly distributed.
06 - Divide the batter evenly among the 12 muffin cups, filling each approximately 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 the tops are golden brown.
08 - Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.