SPOILERS: This post contains details about the Hacks, Season 5 episode ‘Number One Fan’

As Hacks kicks off its fifth and final season, Hannah Einbinder‘s Ava Daniels just celebrated a cameo five years in the making.

Following this week’s episode ‘Number One Fan’, Jesse McCartney revealed that his musical appearance during Ava’s birthday party came as a “full circle moment” after he and his wife first began watching the HBO Max series after it premiered in 2021.

“We fell in love with the show, and then a buddy of mine hits me up like a week later, and he’s like, ‘Hey, have you seen Hacks?’ and I’m like, ‘Yeah, it’s a great show,’ and he says, ‘No, no. Did you see her bedroom?'” he recalled to The Wrap of discovering a poster of himself “circa teen Tiger Beat era” on Ava’s childhood wall in the first season finale.

McCartney DMed Einbinder to confirm what he saw. “She wrote back very graciously: ‘Hey, I’m a huge fan. I grew up listening to your music, and when the producers asked me what would be on Ava’s bedroom wall, I told them it would be you anyway,'” he said.

In the episode, Deborah Vance (Jean Smart) hires McCartney to perform his beloved 2004 single ‘Beautiful Soul’ for Ava’s surprise birthday party.

“I was only on set for a couple hours — it was basically a cameo, but … it was great,” noted McCartney. “I got to meet the whole cast and crew, and everyone was so friendly, and just an amazing group of actors that [are] on the top of their game.”

McCartney noted that Ava’s starstruck reaction was genuine, as Einbinder was struggling to keep it together during his appearance.

“She’s like crying in almost every shot — and I’m not even sure that that was supposed to be in the script,” he said. “And then I saw her at the premiere, and she’s like, ‘It was really hard to find a take where I wasn’t crying in the scene’ … It was really sweet, and obviously getting to work with Jean and Hannah was such an honor.”

Einbinder admitted to The Wrap she was “crying, screaming, throwing up” while working with McCartney. “It was completely real — I was sobbing every single take,” she said.

“It was so authentic, because I actually was a Jesse McCartney stan,” added Einbinder. “I had his posters on my wall from Tiger Beat magazine. I loved him so much, and still do. He’s such a cool guy. He’s really nice.”