Requires: 23cm round cake pan, Electric mixer (or hand beater)
Preheat oven to 180°C conventional oven (400° Fahrenheit/Gas 6). Grease a 23cm round cake pan by lightly buttering the base and sides with margarine or butter. Line the base with baking paper, then lightly butter over the baking paper. Add a heaped tablespoon of 00 flour, then turn and shake the tin to coat the butter in flour on the base and sides of the cake pan.
Using an electric mixer or hand beater, beat the egg whites with a pinch of salt until stiff peaks form. With the mixer (or hand beater) running, add the egg yolks, one at a time. Add the brown sugar, one tablespoon at a time, beating well after each addition.
Use a wooden spoon to stir in the flour, one tablespoon at a time. You want to see air bubbles rise to the surface of the cake mixture before adding additional tablespoons of flour. Stir in the ground almonds, followed by the orange zest and orange juice. Add the margarine (or butter), cinnamon and ginger. Stir the carrots, walnuts and sifted baking powder into the cake mixture until well combined.
Note: 00 is a powder-fine Italian type of flour. It is made from soft wheat varieties, and is frequently used in Italian desserts and pastas. 00 flour is available in most supermarkets, Italian food stores and gourmet delicatessens.
Pour the cake mixture into the prepared cake pan. Bake for 45-50 mins or until a skewer inserted in centre comes out clean. Allow the cake to cool in the cake pan for 10 minutes, then transfer to a wire rack to cool completely.
To make the Lime mascarpone icing, place the mascarpone, cream cheese, icing sugar, lime zest and juice into a large bowl. Use an electric mixer or hand beater to beat the for 1-2 minutes or until just combined.
Do not beat the Lime mascarpone icing for too long or it will start to break down. Refrigerate the Lime mascarpone icing while the cake is cooking and cooling.
Once completely cooled, transfer carrot cake to a serving plate. Spoon the Lime mascarpone icing into a disposable piping bag fitted with a plain round nozzle. Pipe peaks of the icing, starting from the middle and working around in a circle until the top of the cake is covered completely. Serve on the same day of baking – buon appetito.