That Part Was True by Deborah McKinlay. The book is being released by Grand Central Publishing on February 4, 2014.
Amazon says this about the book: When Eve Petworth writes to Jackson Cooper to praise a scene in one of his books, they discover a mutual love of cookery and food. Their friendship blossoms against the backdrop of Jackson's colorful, but ultimately unsatisfying, love life and Eve's tense relationship with her soon-to-be married daughter. As each of them offers, from behind the veils of semi-anonymity and distance, wise and increasingly affectionate counsel to the other, they both begin to confront their problems and plan a celebratory meeting in Paris--a meeting that Eve fears can never happen.