Preheat oven to 350°F (175°C). Line a loaf pan with parchment paper or lightly grease it.
In a large bowl, mash the bananas, then mix in maple syrup, coconut oil, plant milk, and vanilla.
In another bowl, whisk together oat flour, almond flour, baking soda, baking powder, cinnamon, and salt.
Combine wet and dry ingredients and stir until just mixed. Fold in the chopped walnuts.
Pour the batter into the prepared loaf pan. Top with extra walnuts if desired.
Bake for 45–55 minutes, or until a toothpick inserted in the center comes out clean.
Let cool in the pan for 10–15 minutes, then transfer to a wire rack to cool completely.