This is pretty legendary: Frances Ha star (and Golden Globe nominee) Greta Gerwig has signed on to play the titular “I†role in CBS’s How I Met Your Mother kinda-sorta-spinoff How I Met Your Dad. Not only that, but Gerwig will also be a producer on the project and is expected to be one of the show’s writers. The pilot will shoot in Los Angeles, but now insiders say that if it goes to series — something that’s very likely — the show will film in New York City. As previously announced, the project will have completely new characters and stories, borrowing only the flashback storytelling of HIMYM. Gerwig will play Sally, a character being described by the show’s producers as “a female Peter Pan who has never grown up and has no idea of where she’s going in life.†At the show’s start, Sally is facing the end of her one-year marriage, turning to a close circle of friends to help with the pending breakup. Emily Spivey is exec producing the project with HIMYM creators Carter Bays and Craig Thomas.