When former Top Chef contestant Stephanie Cmar quit her job at the James-Beard-winning No. 9 Park, she took what some might consider a step down: She applied for a job at South Campus favorite Mei Mei.

“When I quit No. 9, I did it, well, not hastily, but I didn’t know what I wanted to do,” Cmar said. “I wanted to have a really fun job, so I went on the Mei Mei website. It says ‘HIRE ME, I’M AWESOME,’ and I went, ‘Well, this looks so fun.’”

Cmar never followed up with Mei Mei, but the restaurant doesn’t hold it against her. She was busy creating her next fun job: Stacked Donuts, a pop-up restaurant circulating Boston and Brighton.

Pop-up restaurants are small, chef-driven businesses where a small team (sometimes even one chef) cooks a menu in another restaurant’s kitchen. Some pop-ups last a few weeks, some a few nights, but Cmar’s pop up at Mei Mei Sunday lasted 30 minutes.

“You don’t know what’s going to happen,” Cmar said. “No one could show up, a trillion people could show up … There’s a huge thrill to it.”

Cmar started Stacked Donuts at Barbara Lynch’s Butcher Shop “as a farewell gift of sorts.” The restaurateur let Cmar bake in the kitchen and pop-up in the dining areas on weekend mornings. The first day was so successful she decided to stick with the project. Soon, chefs from around Boston were contacting her, offering their kitchens and support.

“It was just completely organic and unintentional,” Cmar said. “It just happened.”

While Cmar was getting Stacked Donuts off the ground, Justin Burke-Samson and his husband, David, were getting ready to start a family. That is, until they saw how much it cost.

“We did the research and it’s wicked expensive [to raise a child]. There’s no way we could afford it because we both work a nonprofit, so David and I started a fundraising page in lieu of a baby shower.”

The “baby fund” grew, and Burke-Samson started selling baked goods as a thank-you for donors. At a casual lunch, Cmar recommended Burke-Samson join the team, and so Trademark Tarts was born.

“Originally it was going to be cookies, but David said, ‘You need to do your Pop-Tarts,” Burke-Samson said. “So I made the Pop-Tarts, we sold out in 32 minutes, and Stephanie looked at me and said ‘You’re not going anywhere.’”

A Tasty Proposal

Pop-ups generally serve as a win-win for restaurants and traveling chefs. The pop-ups give the restaurants new exposure and a boost in clientele. The restaurants cover a significant portion of the pop-up’s cost of business by providing a cooking space. For instance, when Stacked Donuts and Trademark Tarts held a pop-up at Brookline’s Fairsted Kitchen April 7, drink orders quadrupled.

“Hopefully it’s a give-and-take,” Cmar said. “Without the people who support us, I would be home in bed right now.”

In addition, Cmar and Burke-Samson spend significantly less than they would cooking a traditional menu. According to Burke-Samson, Trademark Tarts spends 6 to 10 percent of their profits on food for a day’s menu. In comparison, Burke-Samson said the average restaurant spends 20 to 30 percent of a day’s profits on food.

Restaurants and chefs are far from the only ones who benefit: Line cooks also enjoy the perks of the pop-up.

“The people that we have help us are the line cooks in Boston, and that’s not a lucrative job at all,” Cmar said. “You just don’t make a lot of money; that’s how it’s always been. So that extra $100, or if it’s two days, $200, is literally a little over a third of their weekly paycheck.”

Alex Kim, Mei Mei’s front house manager, was happy to bring the two chefs into the kitchen as a way to collaborate.

“I really want Steph to be able to reach different demographics all over, and [Boston University’s] demographic is gigantic and something we want a piece of,” Kim said. “I know Stephanie has a huge following on the college campus, and just through working with her every week I really wanted her to be in my restaurant.”

Kim began helping with Stacked Donuts on the side after the two met at Ming Tsai’s Blue Dragon in Fort Point. Mei Mei, which opened its brick-and-mortar restaurant in November, played pop-up around the Boston restaurant community as well.

“It’s really awesome to bring two groups or demographics together and just cross-brand, cross-market and just benefit off each other,” Kim said.

Just Having Fun

Cmar and Burke-Samson tweeted their fair share of selfies — all for the sake of the business, of course.

“Justin and I take a lot of selfies and post really kitschy things because we’re not serious,” Cmar explained. “The true joy of making something like a doughnut or a Pop-Tart is to have fun, you know? It’s not to not enjoy myself. In the last year, so much has happened that has been so serious career-wise that it’s nice to put crushed up Oreos on a doughnut. It’s nice to take a very intentional selfie. There’s a lot of fun to it.”

Cmar began working in traditional kitchens when she was 15 years old. No. 9 Park, where Cmar developed much of her fame before Top Chef, won awards for its contemporary take on the sophisticated European restaurant. When Cmar was promoted to sous chef, she was ready for a change. When asked if she misses working in a restaurant, the answer is clear.

“No,” she said. “Is that too honest? I’ve worked in restaurants since I was 15, and love it, love it a lot, but I’ve never really had anything to claim ownership over, and I really like working on my own terms. I don’t have the same responsibilities, the responsibilities of a kitchen. I have the freedom to do what I want, which is huge and not something you hear about very often. I can be as creative as want, I can bring in people if I want, but really it’s an adventure every time.”

Burke-Samson agreed that keeping it casual is what makes Stacked and Trademark stand out.

“Everyone living in the city gets to a point where you want to find something new to do,” he said. “Pop-ups aren’t new, it’s not a new concept, but I think the way Stephanie and I approach it is by not taking it too seriously. It’s not a mission statement, but sort of a motto, just not to take things too seriously.”

The two chefs try to make sure the food reflects that casual attitude, without sacrificing quality. Playing on nostalgic flavors, Sunday’s menu included cherry limeade and birthday cake Pop-Tarts alongside cookies-and-cream, green tea and blueberry pie doughnuts.

“We’re taking things from our childhood and kicking them up a notch,” Burke-Samson said.

Cmar looked up from a bowl, where she dipped freshly baked doughnuts into sticky-white glaze, rolling them in crushed Oreos before placing them on a cookie sheet. She smiled and held up a doughnut.

“See? Cookies-and-cream. That was my favorite ice cream flavor,” she said. “We’re serious about the quality of everything we put out, but I live life under the saying that if you feel like [expletive] you’re going to produce [expletive]. Nothing good’s going to come out of it.”

As for the future, Cmar and Burke-Samson are enjoying the ride and working with one another, letting whatever happens, happen. The two spoke as one, interrupting one another breezily as they frosted their pastries.

“It’s been really awesome, and people who are watching us are like — ” Burke-Samson started.

“— They’re laughing at us!” Cmar continued. “We have very little cross-over in our lives, other than the fact that he likes baking Pop-Tarts and I like eating Pop-Tarts —”

“ — And it’s great because I have no formal kitchen experience,” Burke-Samson added. “I’m learning so much going around to all these places and Stephanie helping me troubleshoot some things — ”

“—And vice versa!”

“ — And sometimes I help with the flavor ideas, so yeah. It’s great.”

For now, Cmar is enjoying herself, appreciating the spontaneity of Stacked Donuts.

“It’s all been just fun,” she said. “As much as we plan everything, it’s also been unplanned as well, and we’ll just continue to go as long as people continue to invite us, which is both awesome and frightening.”