Preheat oven to 180°C/350°F.
Line the base of a medium sized loaf tin with baking paper.
Bring a small saucepan of water to the boil. Add the apple and simmer gently for around 4 minutes, until soft. Remove from heat and drain through a fine sieve. Discard the liquid.
Beat the eggs and egg whites with a whisk for 30 seconds.
Add all of the remaining ingredients and mix well. Pour the mixture into the loaf tin and bake for 40-50 minutes, until golden brown.
Leave to cool for 5 minutes, then remove from the tin and transfer to a wire rack to cool.