Line a 8" x 4" loaf pan with parchment paper and preheat the oven to 180°C (350°F)
In a large bowl add the almond flour, coconut flour, oat flour, cocoa, salt and the baking powder.
In a medium bowl cream the butter and sugar with a mixer, on medium/high for about 1 minute until lighter in colour and well combined.
Add the eggs to the butter and sugar and beat them for about 30 seconds, then beat in the flax seed and psyllium husk just until there are no lumps.
Add the mashed bananas and beat for another 30 seconds until everything is mixed and somewhat smooth looking.
In a small bowl add the baking soda, stir in the hot milk, then add it to the banana mixture.
Add half of the flour mixture to the wet ingredients and fold it in before beating on low speed, just to combine well. Fold in the remaining flour blend with a wooden spoon.
Fold in the chocolate chips and transfer the batter into the prepared loaf pan.
Bake fo 60 minutes or until a toothpick comes out clean. Allow to cool on a wire rack for 15 minutes prior to icing.
In a medium heat proof bowl, microwave seven large marshmallows for 15 seconds, stir the marshmallows and then microwave them for another 15 seconds.
Transfer the marshmallows to a small saucepan on medium to low heat and stir in 3 tablespoons of water. Add the coconut and icing sugar and stir well until the mixture is easily spreadable. Add another tablespoon of water if the mixture is too thick to spread.
Spread the icing over the top of the loaf, while it is still in the pan and let it cool for 20 minutes..
Store in an airtight container at room temperature for up to 3 days.