For the cake: Preheat the oven to 180C/160C Fan/Gas Mark 4 and line and grease a 12x9inch baking tin. Place the eggs, oil, sugar and maple syrup into a large bowl and using an electric hand-whisk, whisk for 4-5 minutes until well combined, creamy and full of air bubbles.
Sift together the cinnamon, flour, baking power and bicarbonate of soda, then fold into the wet mixture by hand using a silicone spatula or wooden spoon. Finally, stir in the pine nuts and grated carrot. Pour the mixture into the prepared tin and bake in the oven for 30 minutes or until a skewer inserted into the centre comes out clean. Leave to cool in the tin for 10 minutes, then turn out onto a wire cooling rack to cool completely.
For the icing: Place the cream cheese and double cream into a large bowl and whisk using an electric hand-whisk until combined and creamy. Then add the icing sugar and whisk until smooth and creamy. Remove 50g of the icing and place into a small bowl, and mix in a blob of orange food colouring until evenly combined. Then place into a small piping bag, and cut off the end to create a very small hole. Next, take 25g of the icing and place into another small bowl, and mix in a blob of green food colouring until evenly combined. Then place into another small piping bag, and again cut off the end to create a small hole.
To decorate: Place the cooled cake onto a serving board or platter. Then using a small palette knife, swirl on the plain white icing, evenly distributing it over the cake. Then with the orange icing first, pipe small squiggles in an elongated triangle shape, making sure you place them evenly all across the cake. Then using the green icing, pipe small little leaves coming out of the top of the 'carrot' triangles. Serve and enjoy!