Place the orange juice and zest in a bowl with the raisins, stir, cover and leave to infuse for 2-3 hours.
Preheat the oven to 180C/350f. Line an 18cm square cake tin with baking parchment.
Place the sugar and oil in a large bowl, mix together then add in the banana. Whisk it all together with a hand whisk until there a no lumps. Add the eggs and stir again to combine.
Stir in the carrots and infused raisins (including any juice that might be left in the bowl).
Mix the together flour, baking powder, bicarbonate of soda and cinnamon. Add to the wet mix along with the vanilla. Stir until just combined, then pour into the prepared baking tin (it will be runny).
Place in the oven and bake for 40- 45 minutes, until an inserted skewer comes out clean. Leave to cool in the tin for 5 minutes, before removing and cooling completely on a cooling rack.
To make the frosting, whisk together the cream cheese and butter until combined, then add in the confectioners' sugar and orange extract. Whisk together until smooth and creamy. You want a mixture that's thin enough to pour on, but thick enough that it won't just pour off the sides of the cake. If you lift your whisk and the trial remains on top for at least 5 seconds, that should be the right consistency. Add more confectioners' sugar or a drop of water if needed to get it just right.
Pour or spoon the mixture on top of the cake, then sprinkle on the orange zest and cinnamon.
Cut into 16 squares, then serve.
Any leftovers should be covered and stored in the refrigerator. The cake should keep well for 3 days..Nutritional Information is per serving.