Hacks‘ latest episode, “Number One Fan,” sees Deborah (Jean Smart) throw Ava (Hannah Einbinder) an extra-special surprise party following their New York City adventure to secure a slot at Madison Square Garden. Warning: Spoilers for Hacks Season 5 Episode 2 ahead!

In an attempt to prove how well she knows Ava and how close they are, Deborah calls upon their friends to throw the special celebration, but nothing is more thrilling to the writer than the appearance of the singer she loved most growing up: Jesse McCartney. The millennial heartthrob dropped in to sing his classic, “Beautiful Soul,” serenading Ava, her mother, Deborah, and friends for the event, which also featured some culinary delights from Ava’s native Massachusetts, like Bertucci’s and Papa Gino’s.

But how did the guest appearance come together? “Season 1, they asked me if I had posters in my childhood bedroom, who would they be of?” Einbinder recalls of being addressed by showrunners Lucia Aniello, Paul W. Downs, and Jen Statsky. “I said Jesse McCartney and Jesse McCartney is on a poster in Ava’s bedroom when she goes home for her dad’s funeral, and Deborah’s comforting her in her room, so that is the seed for it, and it is true that I had Jessie McCartney posters all over my wall,” Einbinder continues.

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McCartney confirms that is when he discovered Einbinder was a fan, “My wife and I binged Season 1, and we quickly became huge fans of the show. Then a friend of mine said, ‘You need to rewatch one of the episodes. There’s a poster of you in Ava’s bedroom,’ and I didn’t catch it the first time. So I went back and saw it and decided I would DM Hannah, and I didn’t know her at the time, but I thought it was too specific to be an accident. I just had this feeling that maybe she would have something to do with that.”

What unfolded, McCartney reveals, is “She told me she grew up a huge fan, she had even been to one of my shows as a kid, and when the producers asked her who would be on Ava’s bedroom wall, she said it would be me. So I said, ‘Thank you, that’s amazing. Also, if there’s anything you ever want to work on together, let me know.’ And then five seasons later, she and the producers reached out and asked if I would be a part of the show, and it was such a nice moment; I jumped at the opportunity.”

Thankfully, the timing was just right as McCartney only had three days off between tours when he was called up for the gig, which he recounts as a special experience. “I got to meet Hannah, which was really nice, and performing for her and watching her sort of well up and tear up during the performance of ‘Beautiful Soul’ was super special. I felt like a lot of that was actually pretty genuine, and it was really sweet. We got to meet at the premiere and hug it out, and we’re like friends now.”

Einbinder sings McCartney’s praises as well, saying, “He is fabulous and a sweet guy, and I love him, and in a time where many of my heroes have disappointed me, Jesse McCartney has not. That is actually the last man that I can kind of lean on in any way.” In other words, it’s proof that you can meet your heroes sometimes. “As long as they’re Jesse McCartney,” Einbinder clarifies.

Whether or not there was any additional serenading going on, McCartney teases, “We may have jammed out on set to a little ‘Body Language’ or a couple others or ‘How Do You Sleep?’  but those were off camera. I think ‘Beautiful Soul’ was the song most millennials were going to gravitate toward, but yeah, we humored some of the ladies on set with some of the other jams.”

What did you think of Jesse McCartney’s surprise appearance? Let us know in the comments section below, and catch the latest episodes of Hacks as the final season unfolds on HBO Max.

Hacks, Season 5, Thursdays, 9/8c, HBO Max

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