Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or lightly grease it with cooking spray.
In a large mixing bowl, combine the mashed bananas and melted coconut oil. Stir until well combined.
Add the brown sugar to the banana mixture and mix until smooth.
Beat in the egg and vanilla extract until fully incorporated.
Sprinkle the baking soda, salt, and cinnamon over the mixture, and stir to combine.
Gradually add the all-purpose flour, mixing gently until just combined (do not over-mix).
Fold in the chocolate chips and walnuts (if using) until evenly distributed throughout the batter.
Divvy the batter evenly among the prepared muffin cups, filling each about 3/4 full.
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
Notes
Arrange the muffins on a decorative platter and dust with a sprinkle of powdered sugar for an elegant touch. Serve warm with a side of butter or honey for extra indulgence.