Pre-heat your oven to 350°F (180°C) and line a 12-well cupcake pan with paper liners. If you do not have liners then generously grease the wells with coconut oil.
In a large bowl, combine the almond flour, coconut flour, baking powder, baking soda, salt, and cinnamon. Mix well then set aside.
In another medium bowl, mash the bananas well. Add in the eggs, coconut oil, maple syrup, and vanilla. Whisk until thoroughly combined.
Add the wet ingredients into the dry and mix until a thick batter is formed. Lastly, fold in most of the walnuts, reserving some to garnish the top of the muffins.
Transfer the batter to the lined tin, making sure each one is filled 2/3 of the way. Top with the additional walnuts and sliced fresh banana if desired.
Bake the muffins for 25-28 minutes or until golden brown on top.
Allow the muffins to cool slightly before removing from the tin. Enjoy with a cup of tea!
Cover and store the muffins in an airtight container at room temperature for up to 3 days. These muffins can be frozen once baked. To defrost allow thawing at room temperature.