Preheat the oven to 175°C and grease a bread pan.
Mash bananas in a large bowl. Add melted butter, syrup, the egg, vanilla extract, and mix well.
In a separate bowl, add the rolled oats, cacao powder, ground flax seeds, baking soda, baking powder and salt and mix well.
Fold the dry ingredients into the wet ingredients, then fold through the chocolate chips.
Pour batter into the greased bread pan and garnish with extra chocolate chips and walnuts.
Bake in the oven for 1 hour, or until the top is browned and a skewer comes out clean.
Remove from the oven and allow to cool completely before slicing (otherwise it will crumble).
