Jennifer Westfeldt (born February 2, 1970) is an American actress and screenwriter. She is known for co-writing (with Heather Juergensen) and starring in the hit independent film Kissing Jessica Stein. She starred in the 2004 Broadway revival of Wonderful Town. She continues to write scripts and star in television series and films. Westfeldt can be seen on the ABC-TV show Notes from the Underbelly. She is in a relationship with Jon Hamm from Mad Men on AMC..