Preheat oven to 375 degrees. Line a muffin tin with paper baking cups. Note: when ready to place muffins into oven to bake, reduce oven temperature to 350 degrees.
In a large bowl, add bananas, eggs, almond butter, coconut oil, and vanilla. Blend using an electric hand mixer (no need for a stand mixer) to combine the ingredients.
In a small bowl, combine the coconut flour, cinnamon, nutmeg, baking powder, baking soda, and salt – whisk to combine.
Gradually add the dry ingredients to the banana mixture. Scrap the sides of the bowl, as needed.
Fold in 1/2 cup of the chopped walnuts.
Spoon the batter evenly into the lined muffin cups, about two-thirds of the way full.Top each muffin with a few of the remaining walnuts.
Bake at 350 degrees for 20-25 minutes, until a toothpick test comes out clean.
Serve warm or store in the refrigerator in a covered container or re-sealable bag.