Preheat the oven to 350 degrees F and grease a muffin tin with non-stick cooking spray (or line with muffin liners).
In a large mixing bowl, combine the mashed banana, maple syrup, eggs, coconut oil, and vanilla extract. Whisk until very well combined and smooth.
Next, add in the cinnamon, salt, almond flour, tapioca, baking powder, and baking soda. Stir until just combined and smooth.
Fold in the 1/2 cup of the chopped nuts (or chocolate chips, if using).
Evenly distribute the batter into 12 muffin cups, about ¾ way full. Sprinkle each of the muffins with the remaining chopped walnuts. Transfer to the preheated oven and bake until a tooth pick inserted comes out clean, about 12-14 minutes.