It all started with an impromptu strawberry short cake. “I had not a fucking clue what to make,” recalls Momofuku pastry chef Christina Tosi about the day her boss David Chang asked her to make a pastry course for his Ssäm Bar in New York’s East Village.

Up until that point the 29-year-old Virginia native had been Team Momofuku’s utility player: completing payroll, unclogging toilets, writing and maintaining the restaurant’s tricky HACCP plan. “I hired Tosi to help us organize our ‘office’—a desk in a hallway,” writes Chang in the introduction of Momofuku Milk Bar. “Instead, she stared organizing the company.”

Which leads to that buttery short cake. It was no secret that while Tosi was completing the “tit shit” Chang asked of her (an explanation of the term is below), she had her eyes on pastry. After all, she had previously worked under Sam Mason at wd~50 and would often bring in baked goods like toasted miso crack pie for staff meal.

“Every pastry chef in NYC knows how to use local strawberries and really tasty whipped cream to their advantage,” she recalls of the winning dessert that would jumpstart her career running the sweet side of the Momomfuku empire, including four Milk Bars and an insane mail-order business. Next week she will release her first book, which—like the first Momofuku tome—covers not just recipes but the pulse behind what I can easily argue is America’s most-plugged-in restaurant group. We caught up with Tosi earlier this week.

When you open the book up the first thing you see is a photo of you crossing a snowy New York City street, carrying carts of milk and looking really pissed off.
That is the milk delivery, which would happen every Saturday morning. At the time we were working out of this tiny storefront in a little kitchen in the East Village, which wasn’t really designed for a bakery. We formed this huge assembly line through the snowy, dirty streets in the middle of our shifts. At that point I was just trying to make it work.

How is this photo symbolic? I’m reading it as: baking cookies and cakes for a living isn’t all smiles and rainbows.
It is a grueling picture but there is so much passion and perspective behind it. Even the guy who took the picture—he shot the original Momofuku book for us—is like family for us. He knows the whole story.

You write about falling in love with math during college. How does that happen? You just, I don’t know, you just do. I really loved the uphill battle of understanding the way that it works. I really love the problem solving behind it. I love the double-checking of it. I love the accuracy and cleverness behind it. I don’t know, it’s just a love. Like why do you love your favorite pair of shoes?

The editor in me wants to tie your love of math to pastry. It’s tidy. But it’s also not true.
I feel my love of pastry is totally selfish. It was born from being a picky eater and loving to eat desserts and candy and sweets all the time. I also had an obsession with hanging out with my grandmas, who would bake. My passion just grew from that. I think that my love for math was my love for math, and I think a lot of people want to relate it to my love for desserts but I think it’s not at all. My love for baking has nothing to do with numbers. I certainly use math in my everyday life, but that’s that.

What was the most difficult part of writing this book?
Writing the instructional parts. We have these funny terms for either techniques or pans At [Milk Bar] we have this pan that is the sugar pan. And we base a lot of what we do around the sugar pan. So making the recipes understandable for the home cook was the hardest part.

You originally came to work for David Chang as an office manager of sorts. You refer to this as “tit shit.” What?
Yeah, that’s exactly what it was!

Tell me about tit shit.
The editor didn’t want to publish tit shit, but that’s exactly what it fucking was. It’s sort of doing whatever small menial jobs there are. For me, also, I was one of the guys. I was let into this tiny little secret and became the girl that did all the tit shit. Like “You want me to do the payroll this week?” Great! I would work the cash register. “Oh, the ceiling is leaking and the toilet is overflowing?” I’ll call the plumber. I’ll get the snake. That was tit shit.

And it was after all this tit shit—and bringing various baked goods to family meal—that you ended up being asked to create a pastry for Ssäm Bar. What was going through your head when Dave came to you that day?
I really fucking hope he doesn’t call me out on it. He was sort of like go and make something right now. Today’s the day. And I freaked out in my head. Not out loud, because it was a show-no-weakness sort of environment. I had not a fucking clue what to make. I just remember Quino [Baca] was just like “make something, it doesn’t matter. Just make something and make it good.” So I made strawberry short cake. Short cakes are good, they are buttery and sweet.

Is it humanly possible for you to leave Momofuku. You’re so embedded there?
I don’t know. In my head it doesn’t make sense for me not to be here. I don’t really think about it. I feel like I have something really great that belongs to me and I share it with everybody else with their help everyday. I joke that in 10 years I’ll retire. But it will just have to be me Momofuku till I die! Milk bar for life!