Heat the oven to 355°F (180°C)
Line a muffin tray with paper muffin cups.
Mash the bananas with a fork and combine with the maple syrup and almond butter.
Fold in the flour, baking powder, and baking soda and mix well.
Divide the batter between the 6 muffin cups.
Top each one with the walnuts.
Bake for about 18-20 minutes in the middle of the oven, or until a toothpick comes out clean.
Remove the muffins from the oven and cool completely before serving.