With cake week over, the remaining bakers must prove themselves with biscuits. The signature challenge is to create 24 biscotti. Twice baked, these Italian specialities have to be crammed with flavour and have a crisp crunch. It's a delicate balan... (more)ce between underbaked and bendy, or overbaked and rock hard. Paul chooses the technical challenge, arlettes, a labour-intensive reverse puff pastry biscuit from south west France. Wafer-thin, flaky and swirled with cinnamon, delicious to eat but devilishly difficult to make. And finally, the show-stopper is to create and build an edible biscuit box filled with 36 biscuits of a different flavour. Judges Mary and Paul want to see the bakers exercise their creative muscles with clever construction and beautiful decoration, while not forgetting that flavour is king. The pressure is on, and the clock is ticking. Who will claim Star Baker, and who will be leaving the Bake Off tent?