No one is a bigger fan of Shannen Doherty than her bestie, Sarah Michelle Gellar! The cookbook author and actress, 39, spoke exclusively with ET about Doherty’s bravery and strength at the Good Housekeeping Test Kitchen in NYC on Monday.

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“Shannen's incredible. What she's done for other women going through it is... so brave, and that's what real bravery is, is to go through the hardest part of your life and show people, it's OK to be scared,” Gellar said of Doherty, who has been public about her struggle with breast cancer. “And it's OK to be vulnerable, and you can do it.”

Doherty, 45, inspires Gellar all the time. The pals recently attended an intense dance workout class, which they documented on social media.

“The fact that she gets up and goes to those dance classes? The last thing I want to do is go to these really hard dance classes, and sweat that hard and work that hard,” Gellar admitted, “but I have to remind myself, if she's getting up there and doing it, then it's important that I do it, too.”

The Buffy the Vampire Slayer star recently celebrated her hit show’s 20th anniversary, and is now working on a new solo project that features her slaying in the kitchen.

“For me, it's about taking away the intimidation factor,” she said of her new cookbook, Stirring Up Fun With Food. “This is for people who -- even from novice to expert, it's just creative ways to get your creative juices flowing.”

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Stirring Up Fun With Food is out April 4.

For more from Gellar, watch the clip below!

Reporting by Rande Iaboni