'For your signature challenge, Paul Hollywood would like you to make a decorated sheet cake. Sheet cakes are a staple of birthday parties all across America. Your cake must consist of a layer of sponge and a layer of decorative icing. You may incorporate additional elements. Your cake should be presented in 16 identical slices. You have 2 hours.

Paul Hollywood: "The signature bake this week is a classic American sheet cake. Now, what I'm looking for in this is a beautiful, moist sponge packing a nice flavor with an amazing decoration on the top. And the key thing for me is 16 individual cakes that all look the same and taste identical too. It's quite tricky."