Ten years after opening her first Milk Bar, two-time James Beard Award-winning chef and founder of the surprisingly high-tech dessert empire Christina Tosi still sweats the sweet stuff.

Whether she’s opening a new store, as she did recently in LA, inventing a perfect new cookie, or walking on stage at Fortune‘s Most Powerful Women Next Gen Summit in Laguna Niguel, Calif. on Tuesday, Tosi still feels the pain.

“You know, not sleeping, feeling nauseous … I question everything,” Tosi told Fortune’s Beth Kowitt. “I was just raised to never take anything for granted and be on my toes.”

Tosi had a long career in upscale fine dining before she branched out on her own, and the experience was a long, slow exercise in finding herself. “My style is accessibility and shareability,” she says about both the food she makes and the business she’s building. “I did the gut check thing and knew that [fine dining] just wasn’t me.”

But working in the most extraordinary kitchens in the restaurant game helped her hone her skills and find her way. “If my place didn’t exist, it was my job to find a place where I belonged,” she said.

When asked about the challenges and failures that have informed her success, she recalled her first attempt to get big-money investors.

“I started Milk Bar with a small amount of money that David [Chang of the restaurant chain Momofuku] loaned me,” she said. Eight years later, she realized the food business world had changed in ways that would leave Milk Bar behind if she didn’t find smart investment.

Cue culture shock all around.

“I’m a woman and we sell dessert, which is about the girliest thing possible,” she said. “I wasn’t prepared for what a challenge it would be to sit in a room with a bunch of men … questioning my vision and my answers.”

While it was her biggest challenge, it was also her biggest life lesson.

“Never let someone else’s opinion about you quiet the voice that’s deep inside you,” she said.