2) Mix together 1.8kg caster sugar, plain flour, salt, soda, shortening and butter in the bowl of a stand mixer. Mix on 2nd speed for 3 minutes. Then add whole eggs, buttermilk and vanilla to the mixture and beat again for 3 minutes on 2nd speed.
3) In a separate bowl, beat the egg whites and 1.6kg caster sugar into a meringue state. Then gently fold the meringue into the buttermilk mixture. Pour into 4 parchment lined sheet tins or 4 (8- by 26-cm) round cake pans.
4) Bake until a toothpick comes out clean when inserted in the center of the cake.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. the food network kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.