Chef Stacy Cogswell will join chef Rachel Klein at the forthcoming RFK Kitchen. The former Top Chef contender has been keeping busy since her TV days with a New England-centric cookbook and time in the kitchen at Liquid Art House and, most recently, Barcelona Wine Bar in Brookline. Next, she’ll take on the role of chef de cuisine on the RFK opening team. Klein’s new restaurant plans to open its door in Needham come spring.