On NBC’s Superstore, nearing the end of its third season, Canadian actress Lauren Ash plays the overly stern, hilariously blunt assistant manager of Cloud 9, Dina Fox. She’s brash. She’s confident. She’s unapologetic. It’s a role, Ash tells ET, that she was meant to play.

When she first read the script during pilot season, the actress, who previously starred on Super Fun Night opposite Rebel Wilson, immediately connected with Dina. It was very similar to a character that she created years prior at Second City in Toronto. “It was exciting for me, because I know no one else can do this part as well as I do,” Ash says. “Normally I’m not that cocky, but I knew this was my part and I was going to play it.” Four auditions later, it was hers.

Now, over the course of the series, Dina has become more than a sketch character, showing signs of humanity and empathy for her co-workers, particularly her boss, Glenn Sturgis (Mark McKinney), with whom she negotiates to become his and his wife’s surrogate. She still has plenty of uncomfortable quirks -- there’s no shortage of Dina yelling at Sandra (Kaliko Kauahi) to shut up -- but “she’s obviously not a sociopath,” Ash says. “That’s something that’s been really cool to explore in season three.”

And like her co-stars, America Ferrera and Ben Feldman, Ash has expanded her role on the show behind the screen. While Ferrera and Feldman have been stepping behind the camera, making their directorial debuts on Superstore, Ash asked creator Justin Spitzer if she could write an episode for season three. While she’s never written for American television, Ash does have a background in writing, scripting episodes of the Canadian miniseries Trashy Affair. “I just put my hat in the ring,” she says, revealing that she found out shortly before Christmas that she would get to jump into the writers’ room near the end of the season.

Her episode, “Gender Reveal,” which airs Thursday night, will dive deeper into Dina’s pregnancy. “We see her coming to terms with what she signed up for,” Ash says as Dina deals with the changes to her body and her relationship with Glenn. “I think people are going to love the journey we take them on.”

It marks the first time one of the show’s series regulars scripted an episode of the show. “It just really feels like we’re all collaborating and creating this thing together,” Ash says of being able to step in the writers’ room while her co-stars have had opportunities to direct. “It doesn’t feel to me like there’s a lot of ego. It’s like, ‘Let’s make the funniest thing we can.’”

Being the writer of the episode also meant that Ash was on set every day, which allowed her to write and improvise specific jokes for her co-stars. “Normally on the show, I only get to improvise for myself. But when I was a writer, I got to improvise for everybody,” she explains, revealing that some of her favorite lines are the ones she wrote for Kauahi. “She delivered them exactly how I heard in my head and it was so funny.”

While audiences won’t get to see Dina’s baby by the end of the season, Ash has no problem spending more time in the pregnancy suit when the show returns for season four. “You never have to worry about if you look bloated or not,” she jokes, while adding that it was fun to compare her fake pregnancy belly with Ferrera’s real one. (The actress revealed she was pregnant at the beginning of the year.)

“She’s so cute. She goes home on a Friday and comes in on a Monday, and I’m like, ‘You look like you popped even further,’” Ash gushes. “It’s been so adorable to watch her adorable belly pop out. It’s such an exciting time.”

Superstore airs Thursdays at 8 p.m. ET on NBC.

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