Clearly, her casting as the title character was unexpected. "I kind of thought the director, Geremy Jasper, must be insane," she laughs. "I grew up in Sydney, and I started doing acting classes when I was in eighth grade. It was one hour of improv a week, and there was also musical theatre. I loved it, but I was not musical at all. I got stuck in the back of the chorus! But Geremy just had this blind faith."

Danielle in Patti Cake$

Jasper got her to read the role at the Sundance Labs in 2014, and for two years she lived with the character, developing the role alongside costars Siddharth Dhananjay (as Patti's sidekick) and Bridget Everett (as her mother). "Sid, Bridget, Geremy and I, we all developed relationships at the Labs," Macdonald explains. "And by the end of that experience, we all wanted to do the film together. But I never really thought it would get funded with me in the lead. I had a strong feeling this film would get made, but we all thought we'd get replaced at some point for, like, names. But it didn't happen, miraculously."

Playing Patti presented two huge challenges for Macdonald: learning to rap and mastering a New Jersey accent. "I had to learn how to understand rap to learn the songs," she says. "Same with the accent. I listened to both just over and over and over again, because I had to be comfortable enough to be able to go into it if it wasn't a line that I had rehearsed. But there are a lot of words I didn't know in the raps, references to things that I had never heard before, maybe because I grew up in Australia. Some things were definitely just New Jersey-specific lingo. And for some reason I struggled with the word Episcopalian!"

On the other hand, she identified easily with Patti. "I related because I'm in an industry where you don't see many plus-size actresses," Macdonald says. "I love acting and I'm going to continue doing that. The script showed a girl in the same vein, who really wants something and goes for it, and that's a really important message to send out to the world: You can do what you want to do, even when people say no."

Watch the trailer and clips for Patti Cake$: