Katharine McPhee has been set to make her Broadway debut in April when she takes over the lead role of Jenna in Waitress, the Tony-nominated musical based on the movie from Adrienne Shelley that is playing at the Brooks Atkinson Theatre. McPhee, who rose to fame on American Idol and now stars on the CBS series Scorpion, will take over the role April 10 and be in the show through June 17. The role will not impact her …