Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners.
In a large mixing bowl, mash the ripe bananas.
Add the melted coconut oil, maple syrup, and vanilla extract to the mashed bananas. Mix well.
Sprinkle the baking soda and salt over the mixture and stir to combine.
Add the almond milk and mix well.
Gently fold in the whole wheat flour 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 comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.