2) In a large bowl, using an electric mixer, cream the butter and caster sugar together, about 5 minutes. Beat in the eggs, one at a time, then add the lemon zest.
3) In a separate bowl, sift the plain flour, baking powder, bicarbonate of soda and salt. In another bowl, combine the lemon juice, buttermilk and vanilla. Slowly add the plain flour mixture and wet ingredients, simultaneously, into the egg mixture and combine well.
4) Divide the batter between the prepared round pans or sheet pan. Bake for 45 minutes to 1 hour, or when a cocktail stick inserted into the centre comes out clean. Remove from the oven and allow to cool in the pans.
5) Slice, as desired, and serve.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Chefs have not tested this recipe, in the proportions indicated, and therefore we cannot make any representation as to the results.