Preheat the oven to 375F. Grease a 12-cup muffin tin and set aside.
In a large mixing bowl, beat all wet ingredients together (including the bananas and the sugar) until fully combined.
Add the dry ingredients to the banana mixture and stir to combine, until you have a nice smooth batter.
Spoon the batter into the muffin tins, filling each cup about ¾ of the way full. Top each muffin with some walnuts and gently press down so that walnuts stick as the muffins bake.
Bake in the center of a warm oven for 13 - 15 minutes, or until a cake tester inserted into the center comes out clean.
Let the muffins cool for 10 minutes on a wire rack.
Enjoy these muffins served warm, topped with vegan butter, jam, or your favorite nut butter.
Store leftover muffins in an airtight bag on the counter for 4 days, or in the fridge for 1 week. You can also double bag and store in the freezer for 5 months. Reheat in a toaster oven on medium heat, or in a microwave on 80% power in 15-second increments.