Preheat your oven to 350°F (175°C). This ensures that your muffins bake evenly and rise properly.

Grease a muffin tin with non-stick spray or line it with muffin liners to prevent sticking.

In a large mixing bowl, mash the ripe bananas with a fork until smooth. This adds natural sweetness and moisture to the muffins.

Add the Greek yogurt, honey, eggs, and vanilla extract to the mashed bananas. Whisk together until well combined.

In a separate bowl, whisk together the whole wheat flour, protein powder, baking soda, baking powder, and salt. This helps to evenly distribute the leavening agents and ensures a fluffy texture.

Gradually add the dry ingredients to the wet mixture, stirring gently with a spatula until just combined. Be careful not to overmix, as this can lead to dense muffins.

If using, fold in the chopped walnuts for added texture and flavor.

Spoon the batter evenly into the prepared muffin tin, filling each cup about ⅔ full.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean. This ensures the muffins are fully cooked.

Once baked, remove the muffins from the oven and let them cool in the tin for 5 minutes.

Transfer the muffins to a cooling rack to cool completely. This helps maintain their texture.