Preheat oven of 425 degrees and line a muffin tin with parchment paper muffin liners.
In a large bowl add all of the dry ingredients. Mix until combined.
In a medium bowl, mash the banana and then add the rest of the wet ingredients. Mix again.
Add the wet ingredients to the dry ingredients and mix until combined. Add chopped walnuts and mix again.
Fill the muffin tin with the batter and bake for 16 minutes.
Let cool for about 15 minutes and then enjoy!