Start by lining a loaf tin and preheat the oven to 160C.
Blend together the bananas, avocado, nut butter, maple syrup, milk, vanilla, espresso and apple cider vinegar until completely smooth.
Next, stir together the dry ingredients – the flour, protein, almonds, coconut sugar, bicarb and baking powder, salt and cacao – until combined.
Stir the wet ingredients into the dry ingredients until combined, then stir through the chocolate chips, adding a tablespoon or so of milk to loosen, if needed. Spoon into the prepared loaf tin and place in the oven to bake for around 1 hour and 10 minutes, or until the cake is cooked through and a skewer comes out clean. Remove from the oven and leave to completely cool.
In the meantime, gently melt the chocolate for your frosting in a bain marie with the coconut oil. Place in a blender with the remaining ingredients and blend until smooth. Spread the frosting over the cooled cake, then cut into slices and serve.