For the final technical challenge Mary Berry asked the bakers to make this simple sponge with homemade jam and buttercream – without a recipe. For this recipe you will need two sandwich tins, an electric mixer and piping bag fitted with plain nozzle.
Due to popular demand here is the recipe for Mary Berry's Chocolate Tray Bake (from the Mary Berry Ultimate Cake Book). The icing can be difficult to make just because of the amount of icing sugar,. (cake making mary berry)