01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - Mash bananas in a large bowl until smooth. Whisk in eggs, Greek yogurt, honey, oil, and vanilla extract until thoroughly combined.
03 - In a separate medium bowl, whisk together whole wheat flour, baking soda, baking powder, cinnamon, and salt until well blended.
04 - Gradually fold dry ingredients into the banana mixture. Stir gently until just combined—batter may remain slightly lumpy. Do not overmix.
05 - Gently fold in chopped walnuts or pecans. Add dark chocolate chips if using.
06 - Divide batter evenly among prepared muffin cups, filling each about three-quarters full.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean and tops are golden brown.
08 - Let muffins cool in the pan for 5 minutes. Transfer to a wire rack to cool completely before storing or serving.