Preheat your oven to 350°F (175°C). Grease a muffin tin or line with muffin liners.
In a large mixing bowl, mash the ripe bananas until smooth.
Add the melted coconut oil, maple syrup, and vanilla extract to the mashed bananas. Mix well.
Stir in the baking soda and salt.
Add the almond milk and mix until combined.
Gradually add the whole wheat flour and mix until just combined. Do not overmix.
Fold in the chopped walnuts.
Divide the batter evenly among the muffin cups.
Bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.