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A colorful slice of cake with a matrix background. Lille Allen

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The Big Bake Theory

Enter the matrix of Bluejay Patisserie in the San Gabriel Valley, run by pastry chef Jay Chen and her software engineer husband, Ivan Lo

Cathy Chaplin is a senior editor at Eater LA, a James Beard Award–nominated journalist, and the author of Food Lovers’ Guide to Los Angeles.

One of the more intriguing features on Patisserie Bluejay’s website is the “cake picker,” a sparse flowchart PNG designed to help customers choose their ideal cake from the bakery’s three dozen or so options. The diagram, which looks like a pastel-ified corporate organization chart, begins with customers selecting from three broad flavor buckets: pure chocolate, pure fruit, or pure cheesecake. The questions that follow dig deeper into taste and textural preferences, allowing the cake picker to eventually whittle the abundant choices down to a single perfect cake. Welcome to the wonderfully left-brained world of Patisserie Bluejay.

Tucked into a dusty Arcadia strip mall anchored by a 99-cent store, the shop is the work of pastry chef Jay Chen and her software engineer husband, Ivan Lo. Patisserie Bluejay, which is named after Chen and an episode of The Big Bang Theory, devotes a day each week to research and development, continually revises its recipes, and sells updated versions of its cakes and pastries. While the corner bakery looks fairly standard from the outside, with its pale yellow walls, tile flooring, and wood-trimmed pastry case filled with cookies, cream puffs, and canelés, a conversation with the owners reveals that this isn’t an ordinary dessert operation — it’s the nerdiest sweets shop in Los Angeles.

Left to right: Pastry chef Jay Chen and her software engineer husband, Ivan Lo, at Patisserie Bluejay.
Left to right: Pastry chef Jay Chen and her software engineer husband, Ivan Lo.
Chen decorating a tom yum cake at Patisserie Bluejay.
Chen decorating a cake inspired by the aromatic Thai soup tom yum goong.
Chen decorating a tom yum cake at Patisserie Bluejay.
Chen adding fresh mint leaves atop the tom yum cake.

Chen and Lo opened the bakery in February 2023 after spending years refining recipes and searching for an ideal location. The two met in Hong Kong around 2011 and married in 2019. Before that, Lo divided his time between China and the U.S., while Chen lived and worked in Hong Kong as a chef (first as a private baker specializing in birthday cakes and then as the sous chef of a vegetarian restaurant in Wan Chai). After moving to Los Angeles, Chen, who spoke to Eater through Lo’s translations, needed help navigating the intricacies of starting a small business from the ground up; Lo was happy to jump in to help open and run the bakery alongside his wife while balancing a full-time software development job.

Patisserie Bluejay gleans its cake-making approach from tech start-up culture and even applies elements of design thinking to its recipes. Chen’s lineup of understated and meticulous cakes is underpinned by French techniques and features Asian flavor mashups that are wholly her own. “We’re ultimately a French and Asian fusion bakery,” says Lo. “Our palates cater more to Asian palates but we are more Western compared to [traditional] Chinese bakeries.”

Patisserie Bluejay’s layer cakes taste lighter than they look, more similar to a firm English trifle than a standard American bakery slice. Chen achieves the texture by interspersing layers of mousse with a Bavarian cream that mimics the mouthfeel of sponge cake. “The mousse will give you that melty feeling while the sponge cake is slightly coarse so your tongue can be gently massaged by that micro-contrast feeling,” Lo wrote about the cakes’ composition in an Instagram post.

Chen and Lo opened the Bluejay Patisserie in February 2023.
Chen and Lo opened the bakery in February 2023.
Bluejay Patisserie’s selection of cakes by the slice changes daily.
Cake flavors are inspired by cocktail culture, savory dishes, candy makers, and occasionally, YouTubers.

Rather than look to existing cakes sold at competing bakeries to inform their menu, Chen and Lo take cues from cocktail culture, savory dishes, candy makers, and occasionally, YouTubers. The couple spends hours debating possible flavor combinations to test, like marrying white sesame seeds with an Italian tiramisu or pairing dark chocolate with the sharp heat of wasabi. Often, these impromptu brainstorms dominate their dinnertime conversations and fill the drive to Arcadia from their home in Glendora. Their list of potential cakes and pastries is 100 ideas long, and they’ve only attempted a third of them thus far, says Lo.

While pastry chefs tend to sell only perfected versions of their creations, Chen and Lo take an approach that includes baking multiple prototypes and inviting customer collaboration along the way. Applying an engineer’s mindset to cake making, Chen’s recipes, many of which originated in Hong Kong, are constantly tweaked and improved upon. “Software has bugs, some flaws, it’s not perfect,” says Lo. “We embrace the imperfections, we know that our product coming out will be not perfect and subject to change.” Lo often shares research missteps — burnt and misshapen canelés or kitchen experiments — on social media, a rarity among the polished Instagram feeds of most bakeries. It’s this candor and commitment to quality that has won the bakery a legion of invested fans.

Every slight recipe adjustment, no matter how subtle, is documented in a notebook or “a repository,” as Lo refers to it in programmer parlance. Chen and Lo keep track of different iterations through versioning, assigning sequential numbers to each recipe that reflect major or minor changes. “We think pastry or cake making is one of the most scientific jobs,” says Lo. It takes about two weeks to develop an initial prototype and around one to two months to settle on a “stable” version, says Lo.

With each recipe, Chen also considers how the cake’s various components, like mousses and gelées, are uniquely layered, dispersed, and consumed. She designs each bite so that different flavors and textures come into play at different moments. “We strategically put more ingredients in the tip of the [slice],” says Lo. “That’s when you are starting from nothing, your mouth is neutral and you will be more sensitive to flavors like sourness or bitterness or any fruity flavor.” Chen wants the first bite to be distinct from the final one, so rather than uniformly layering different components horizontally (“because horizontal is just giving you everything together at once,” Lo says), she treats them like Tetris pieces that can move and change vertically. “We tend to put longer lasting flavors toward the final bite, like osmanthus flower, jasmine flower, or rose,” says Lo.

Rose and lychee cake at Bluejay Patisserie.
Rose and lychee cake.
A slice of rose and lychee cake at Patisserie Bluejay.
A slice of rose and lychee cake.
Oolong and peach cake at Bluejay Patisserie.
Oolong and peach cake.
A slice of oolong and peach cake.
A slice of oolong and peach cake.

The bakery recently landed on a stable version of its popular pear and Moscato cake, inspired by a traditional Cantonese drink that combines the fruit with the osmanthus flower. The first version, referred to internally as 1.0, was made with sparkling Moscato until the couple found that the carbonation yielded a less assertive wine flavor than they desired. (The Moscato’s price point also cut into profit margins.) Chen swapped out Moscato for pinot grigio for the next version, but their customers, who live nearby and regularly volunteer to taste test, found the flavor too subtle again. In version 3.0, Chen added pinot grigio to the cake’s gelée topping and laced the Bavarian cream with pears sous vide in white wine. After months of tireless trial and error, the ratios of wine to fruit and tea were finally just right. “Unless a customer comes up with a brilliant suggestion,” says Lo. “It’s pretty stable.”

The patisserie’s latest cake project riffs on the aromatic Thai soup tom yum goong. “We are trying to find a balance between lemongrass and lime,” says Lo. “We can’t decide whether to make this a tangy cake or not.” Early customer feedback led Lo and Chen down a more citrusy path with the first version, which included pureed Granny Smith apples. While version 2.0 ditched the fresh fruit, it returned in version 3.0 as part of the mirror glaze atop the cake. After a month and a half of testing and tweaking, Chen landed on the fourth and potentially final version of the cake. “It should be the stable one,” says Lo.

Going against the grain is woven into Patisserie Bluejay’s DNA. This bold sensibility carries over into how the couple approaches success as well. Given the bakery’s intensive research and development processes, Lo says they accept that it may never be financially lucrative. Without tethering the bakery’s value and contribution to its bottom line, Chen and Lo have the freedom to define for themselves what success looks like. A true win for Lo would be tackling all 100 ideas on their running list of possible cake flavors. As for Chen, she wants to build lasting memories with her customers.

“She thinks that birthdays are quite important and the things you eat on a birthday can let you remember for life,” says Lo. “To leave that kind of point in time in the memory, she’d be happy about that.”

Patisserie Bluejay

160 E. Duarte Road, Arcadia, CA 91006 Visit Website
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