Preheat your oven to 350°F (175°C) and line a 9×5-inch loaf pan with parchment paper, letting it hang over the sides for easy removal.
In a large bowl, thoroughly mash the bananas with a fork until no chunks remain.
Whisk in the melted coconut oil, maple syrup, plant milk, and vanilla extract until well combined.
In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon.
Gently fold the dry ingredients into the wet mixture until just combined (do not overmix).
If using walnuts, fold them in now with just a few strokes.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Tap the pan gently on the counter a few times to release any air bubbles.
Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean with just a few crumbs.
Allow the banana bread to cool in the pan for about 10 minutes, then use the parchment paper to lift it out onto a wire rack.
Cool completely before slicing for the best texture.