In a large bowl, mix together the baking soda, salt and flour. Set aside.
In a second large bowl, use a hand blender to cream together the chia egg, bananas, white sugar, brown sugar (except the extra 1 tbsp), vanilla and oil until smooth.
Slowly add in the flour mixture to the wet ingredients, keeping the hand blender on in between to mix the ingredients as you add them. Be careful not to over mix - just run the blender for a few seconds each time.
Continue this until the dry ingredients are fully incorporated into the wet ingredients.
Fold in the ½ cup walnuts (reserving the extra ⅓ cup) and ½ cup of dried cranberries with a spatula.
Lightly grease 8x8 inch baking tray with avocado oil, then line it with parchment paper.
Pour the banana bread mixture evenly into the pan.
Sprinkle the brown sugar and 1/3 cup of walnuts evenly over the mixture.