In a food processor blend the plantain, banana, coconut milk, coconut oil, raw apple cider vinegar until smooth but still a thick texture. Meanwhile mix the other dry cake ingredients in a bowl.
Mix the wet mixture into the dry flour mixture until smooth.
Pour into greased and lined 2lb/900g loaf tin and smooth the top of the cake mixture.
Cook until firm and solid in the middle.
Remove from oven and allow to cool.
ICING
Whisk all the icing ingredients in a bowl and then spoon onto cooled cake and place in the fridge for the icing to harden and set.
Notes
Coconut flour can vary in absorbency so if needed add more water or coconut milk a little at a time