The week's best amateurs are put through the mill with a seriously daunting test - the critic's brief. The home cooks have to impress just one food critic with two dishes. They are given the critic's brief and must create a main and a pudding based on it. The brief has been set by eagle-eyed and astute food critic William Sitwell, who asks them to cook a main based on the following instructions: 'I enjoy spicy dishes and I am looking for a cook who understands how to get the best out of ingredients. I want to see a light touch - a cook who is being guided by the ingredient and what the ingredient calls out for, not what he or she thinks is trendy or will impress.' After cooking their main dish based on this brief, but without knowing who has set it, the contestants are finally introduced to their critic and must stand before him with their dishes. Face to face, they will hear exactly what William Sitwell, as well as John and Gregg, thinks of the mains and how well they have kept to the brief. After this searing honesty, the quarter-finalists must return to the kitchen and prepare a dessert that fulfills William's brief: 'I love classic English puddings - blackberry and apple crumble, treacle tart. I love a good tarte tatin.' At the end of tonight's quarter-final, three cooks will go through to Knockout Week, taking another step closer to being crowned MasterChef Champion 2015. For one, their MasterChef dream will be over.