But at the end of the night, it also included the 79-year-old Mitchell herself, eight years after a brain aneurysm that forced her to relearn how to walk and sing, performing an exquisite version of George Gershwin's "Summertime" in a voice far different from but just as powerful as the one she used on her hit recordings.

She sang "Summertime" with her hand on the piano where the show's Emmy-nominated musical director, Greg Phillinganes, was sitting.

"It was just as stunning as you think it would be," Phillinganes, a veteran session musician, recording artist and sideman for the likes of Stevie Wonder and Michael Jackson, told TheWrap. "It's nothing short of a miracle that she's back to the level that she is. Her tenacity, her will to want to not just survive but thrive, all that came into play.

"And then when I found out that she wanted to stand right at the nook of the piano to sing 'Summertime,' I thought, Well, I can die and go to heaven now, because it's not going to get much better than this," he added.

Mitchell, Phillinganes continued, had already chosen the band when show producer Ken Ehrlich asked him to be musical director. She signed off on Erhlich's choice even though she and Phillinganes had never worked together. "I figured she didn't know me from a hole in the wall, you know?" he said. "So I was very pleasantly surprised and honored that she would say OK when Ken suggested me."

With most of the guest singers already in place when he came on board, his priorities were simple: "Make sure all the artists are happy."

He laughed. "That's it. It's 90% psychology, and just having a connection with each artist, understanding their personalities, their quirks, their needs, their likes, their dislikes, while at the same time having a vision strong and effective enough to carry through.

Riley Keough Reveals What Made Her Stay on 'Daisy Jones,' Even When She Wanted to Quit "It's a mutual effort, a cooperative effort," Phillinganes said. "First of all, they have to trust me, like I trust them. Having a reputation for integrity and results doesn't hurt. These artists know that my priority is their comfort level, and I have a solid understanding of who they are musically and personally. And many times it evolves into personal relationships, like the kind I have with Annie. I got to know Cyndi a lot better, too, during this process. Angelique is a force of nature, and it's always great working with her. And to be able to reconnect with J.T. [James Taylor] again after I don't know how long it's been since I'd last seen James, it was wonderful."

At the center of it all was Mitchell, finding a powerful new voice to pay tribute to Gershwin while Phillinganes played along from a few feet away.

"She is just as much of a sweetheart as she is a grand dame," he said. "She's as overwhelming as you think she may be, but she doesn't come off that way at all. She could not have been more accommodating.

"It was just an incredibly wonderful feeling to accompany her, especially at this stage of her life," he added. "She was phrasing in new ways to compensate for certain things that she may have been lacking, but it was pure and strong. And it still was her, you know? There was no mistaking her."