The Tony Award winner of Thoroughly Modern Millie offered what many viewed as one of the most inspired musical moments in the Mel Brooks show when, in the middle of a song called "Roll in the Hay," she began yodeling. (The hay ride scene is famous in the film that inspired the musical; Teri Garr played Inga in the picture.)

Starting July 8, the yodeler who catches the eye of the title character, played by Roger Bart, will be Kelly Sullivan (Contact, Bells Are Ringing). Foster is in rehearsal to play Fiona in the Broadway-bound Shrek the Musical.

Beth Leavel (as Frau Blucher) and Michele Ragusa (as Elizabeth) will join Young Frankenstein in the coming weeks. The remaining original cast members include Bart, Shuler Hensley, Fred Applegate and Tony Award nominee Christopher Fitzgerald.

Tony winner Leavel (The Drowsy Chaperone) steps in July 22, and Ragusa (Adrift in Macao, Paper Mill's Kiss Me, Kate) takes on the role of the cold girlfriend of the title character Aug. 5.

Andrea Martin — Tony-nominated for her performance — completes her Weill-esque turn as Blucher July 20, and Megan Mullally (as Elizabeth) will depart after the Aug. 3 performance. Young Frankenstein, with book by Brooks and Thomas Meehan and music and lyrics by Brooks, was named Best Broadway Musical 2008 by the Outer Critics Circle Award.

The musical comedy is based on the Oscar-nominated hit 1974 film of the same name. It's "the wickedly inspired re-imagining of the Mary Shelley classic from the comic genius of Mel Brooks," according to producers. "When Frederick Frankenstein, an esteemed New York brain surgeon and professor, inherits a castle and laboratory in Transylvania from his grandfather, deranged genius Victor Von Frankenstein, he faces a dilemma. Does he continue to run from his family's tortured past or does he stay in Transylvania to carry on his grandfather's mad experiments reanimating the dead and, in the process, fall in love with his sexy lab assistant Inga?"

Set in "the forbidding Castle Frankenstein and the foggy moors of Transylvania Heights," the show's score includes "The Transylvania Mania," "He Vas My Boyfriend" and a singular treatment of Irving Berlin's "Puttin' On the Ritz."

For more information visit YoungFrankensteinTheMusical.com or Ticketmaster.com or call (212) 307-4100.