Preheat your oven to 180C/355F.
Grease 12 muffin cups/tins with butter or non-stick cooking spray.
In a food processor or blender, blend your bananas, mango and egg whites until smooth and combined.
Add in all of your other ingredients and process until combined, scraping down the sides in between processing to ensure everything is mixed together.
Pour your mixture into your prepared cups/tins, filling about 3/4 of the way full.
Bake for 15-20 minutes or until cooked through and a skewer inserted into the centre of one of your muffins removes clean.
Allow to cool before serving or storing in an airtight container. These will keep for 2-3 days in an airtight container at room temperature, up to a week in an airtight container in the fridge or for months if frozen.