Mulgrew has departed the Paper Mill production due to a schedule change, according to the New Jersey venue.
Directed by Wendy Goldberg, the award-winning Terrence McNally drama will play the Paper Mill March 4-April 5. Walsh will be joined onstage by Sarah Uriarte Berry (Sharon), Andrew Gerle (Manny), Mike McGowan (Tony), Lauren Worsham (Sophie) and Ryan King (Stagehand).
Master Class, according to press notes, "is the story of renowned opera diva Maria Callas teaching a master class in front of an audience: us. She's glamorous, larger than life, and drop-dead funny. What begins as a class becomes an intimate and revealing look into her life: we learn about Callas' tumultuous affair with Aristotle Onassis, her early days as an ugly duckling; the fierce hatred of her rivals; and the unforgiving press that savaged her at first."
The production will feature scenic design by Alexander Dodge, costume design by Anne Kennedy, lighting design by Josh Epstein, sound design by Randy Hansen and hair and wig design by Chuck LaPointe. The production stage manager is Barbara Reo.
Paper Mill Playhouse is located at 22 Brookside Drive in Millburn, NJ. For tickets call (973) 376-4343 or visit www.papermill.org.