In the last quarter-final, the four best chefs from this week's heats come together to compete in two challenges set by judges Anna Haugh and Marcus Wareing. To earn the last two places in the semi-finals, the chefs must show off their creativity in an invention test, then prepare food for some of the UK's most hard to please food critics. Only the most exciting culinary talents will continue in the competition.In the first challenge, the judges set a pastry Invention test with a twist: the dessert must be based on a savoury ingredient. Next to the classic pastry ingredients in the larder, the chefs have cheeses, bacon, vegetables, chillies and herbs to build their dishes around.Then, the chefs face one of the toughest rounds of the competition. In just one hour and fifteen minutes, they must serve up an exceptional two-course meal to three of the country's biggest restaurant critics. This is their chance to shine as they cook for people who could one day make or break their careers.