"The Notebook" will bring its enduring love story to Broadway.
"I have a surprise," she told Kotb. "I'm writing a musical -- and the musical is 'The Notebook!'"
Michaelson is working with screenwriter and "This is Us" producer Bekah Brunstetter on the project. Michaelson will write the music and lyrics, with Brunstetter to pen the book.
"I've been writing for about a year and half, so it's been a long process for me. It's been slowly building, slowly building," Michaelson said.
"The Notebook" is a 1996 novel by author Nicholas Sparks, who will produce the musical adaptation.
The book was previously adapted as a 2004 film starring Ryan Gosling and Rachel McAdams.
"They are amazingly talented, and obviously, the story is near and dear to my heart."
Michaelson said she had to excuse herself to the bathroom to cry after she was approached about the project.
"I have loved the movie and the story for so many years now that the idea of turning it into a musical overwhelmed me," the star explained.
"The concept of unending devotion and love wrapped up in memory and family is something very close to my own personal life. The story sings to me so perfectly," she said.
Kevin McCollum and Kurt Deutsch will produce "The Notebook" musical alongside Sparks.