It’s not often that a high-school friendship blossoms into a successful professional relationship, but writer-director Dave McCary and his best friend Kyle Mooney have pulled it off. After college, the duo founded Los Angeles-based sketch comedy group Good Neighbor (with Beck Bennett and Nick Rutherford), developed a huge YouTube following (Louis C.K. and Steven Spielberg are fans), and were snatched up by Saturday Night Live.

Now, nearly four years later, McCary is making his feature directorial debut at Cannes with Brigsby Bear, which stars and was co-written by Mooney, with Kevin Costello. Featuring stellar guest appearances from the likes of Claire Danes, Mark Hamill, Greg Kinnear and Andy Samberg, the film is scheduled to close the Cannes Critics’ Week sidebar.

“I’ve been very fortunate to be working alongside my best friend over the past couple of decades,” says McCary, “from our high school band to internet videos, to SNL to this film. I think we’ve faced all the typical challenges that young filmmakers go through over the years—time, money, negativity—but it’s a lot easier to manage when you can learn from and laugh about all those mistakes and anxieties with your best pal.”

Picked up by Sony Pictures Classics for $5 million after it premiered at Sundance, Brigsby Bear is a quirky comedy about a children’s TV show with a twist—it’s produced for an audience of one (Mooney), and when the show abruptly ends, he sets out to finish the story himself.

“Kyle had been thinking about this idea for years,” recalls McCary. “We’re big fans of dated, obscure thrift-store VHS finds, especially regional Christian educational kids videos, and I remember Kyle explaining to me the seed of this idea maybe five years ago, where an animatronic bear show was being made just for him as a brainwashing tool. I obviously loved it.” When they were hired by SNL, Mooney gave the idea to another childhood friend (Costello). He wrote a rough script, and three years later they were “running around Utah with a camera and an animatronic bear head.”

Of his Cannes debut, Mooney says, “I’ve certainly dreamed of having a film at the festival since I first started making videos in high school. It’s all very surreal and special, and I hope I don’t embarrass myself.”