Preheat the oven to 190 degrees C and grease a rectangular baking tin.
Whizz up the banana and apple slices until you get a smooth puree, then put in a large bowl with the eggs, peanut butter and vanilla – beat well until thoroughly mixed.
Add the rest of the dry ingredients to the bowl and beat well until combined and you get a smooth batter, then pour into the tin and spread evenly. Bake for about 15-20 minutes until risen and golden. Remove, slice into bars and leave to cool.
Prepare the icing – melt the coconut oil in a small pan, then add the cocoa powder, Natvia and coconut milk – keep at a low heat. Mix the cornflour with a little cold water to make a paste then whisk into the pan while still cooking. Whisk well until you get a smooth thick ‘sauce’.
Remove from heat, then move quickly and spread a spoonful or two over each bar until covered on top. Return to fridge until ready to serve – either eat straight away chilled or bring to room temperature. NOM!