2) In a stand mixer, mix the butter and shortening with the paddle attachment on medium speed until combined. Add the granulated sugar, cream and salt, starting on 1st speed and gradually moving to 2nd speed, until light and fluffy approximately 8 minutes.
3) At 1 1/2 speed add the egg whites in small amounts until smooth and fully incorporated. On 1st speed alternate 1/3 dry ingredients, 1/2 milk, 1/3 dry, 1/2 milk, 1/3 dry only until incorporated.
4) Pour the batter into greaseproof paper lined sheet tins or four 32cm round by 10cm deep cake tins and bake for 30 to 45 minutes or until a cocktail stick inserted into the centre of the cake comes out clean.
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.