By Jesse Newman | Photographs by Elizabeth Renstrom for WSJ

Senior employees from sweets-and-snacks giant Mondelez slipped into a conference room at the Pennsylvania headquarters of archrival Hershey on a spring day three years ago. They were there to discuss a merger.

The tie-up on the table wasn't a typical corporate combination. Hershey makes Reese's peanut butter cups. Mondelez makes Oreo cookies. It was time, the companies decided, to unite them. Hershey would infuse Oreos into its nutty confection, and Mondelez would fill Oreos with Reese's peanut butter, finally satisfying the cravings of the brands' most ardent fans.

In theory, the idea behind the products was simple. In practice, merging two of America's most iconic snacks, while maintaining their individual identities, was a deeply complex undertaking, requiring cloak-and-dagger tactics reminiscent of the Manhattan Project. Executives and food scientists met in secret and spoke in code, keeping knowledge of the effort to a tight circle to prevent leaks.

Experimental cookies and candy under development were hidden in foil wrapping while company officials shuttled to and from corporate offices and the research-and-development labs where recipes were being tweaked.

Throughout it all, both camps' leaders strove to ensure the taste of their flagship product didn't get buried by the competition.

"Can I identify the flavor profile of my Oreo in your product?" said Norberto Chaclin, Mondelez's head of R&D. "Or is it being overpowered by your peanut butter?"

After four months, the two teams gathered again at Hershey's compound to taste the first stab at a Reese's Oreo Cup.

The verdict: This collaboration needed work. A lot of work.

Seeking a hit

For Hershey and Mondelez, the stakes were high. Reese's and Oreo are the two snack companies' top-selling products -- decades-old stalwarts of supermarket aisles and convenience-store racks, carefully managed and fiercely protected. Both brands generate billions of dollars' worth of sales each year from their classic incarnations wrapped in crinkly plastic -- and from ice cream flavors, spreads, syrups and bars. (The original Reese's and Oreos aren't going away when the new treats hit the shelves. No one thinks this combination is that good an idea.)

The companies could use a hit. The pandemic-driven sales surge for big food makers is long over. The years of inflation that followed left consumers scrutinizing price tags and rethinking their shopping lists.

As prices of agricultural commodities from beef to coffee have risen due to supply crunches, sweets makers are facing one of the steepest climbs of all. The cost of cocoa shot to a record last year after heavy rains exacerbated crop disease in Western African growing regions, followed by a blast of hot, dry weather.

Americans as a result are eating less chocolate, while paying more. Both Hershey and Mondelez are raising prices in order to offset higher costs, and the Trump administration's trade battles could push prices higher still. Hershey last month dialed back its full-year profit forecast to account for the added cost of tariffs. Meanwhile, Health Secretary Robert F. Kennedy Jr.'s "Make America Healthy Again" movement has added another curveball, ratcheting up scrutiny of processed food.

Fan service

The companies have tried fusing Reese's and Oreos before. In 2014, Mondelez debuted a limited-edition Oreo cookie with Reese's peanut butter filling. The brief union touched a nerve, the companies said, and fervent fans have clamored for a redux.

Some didn't wait. For years, DIY mashups have circulated on TikTok and Instagram -- videos showing people munching on a Reese's cup sandwiched between two Oreo wafers, or scooping peanut butter out of a cup for use as a cookie filling. Others mixed Reese's and Oreos into baked goods or ice cream sundaes. Such posts from fans and "snackfluencers" have racked up more than 260 million views.

It was April 2022 when a handful of senior employees from the two companies first gathered at Hershey's headquarters to discuss the idea of a dual-track collaboration.

For Mondelez, the task was creating a double-stuffed Oreo that looked and tasted like the 113-year-old classic, while working in Reese's trademark peanut butter.

Hershey's mission was to incorporate Oreo's signature cocoa-cookie crunch and vanilla creme into its tried-and-true peanut butter cups.

Adding to the challenge: No one would be sharing any recipes.

The blueprints for both Oreos and Reese's peanut butter cups are closely guarded secrets, and neither company was eager to provide details about its No. 1 product to a competitor. So Hershey and Mondelez had to figure out a way to get their offerings to taste like the others without knowing their rival's exact formulas.

As the projects got under way, lawyers were called in to draw up contracts and intellectual-property agreements. Terms of the collaboration ultimately included details like how much Oreo will be used in the final Reese's product.

The companies devised code names to refer to the projects. Mondelez's was "Project Snoopy," an homage to the beloved "Peanuts" character. Hershey's was "Project Powerplay."

As work kicked off on the Oreo, only about a dozen people at Mondelez were aware of the collaboration, said Justin Parnell, the company's senior vice president of marketing and insights for North America.

Oreo dust

Unlike Mondelez, Hershey had never tried to incorporate its rival's top product into its own. Early on, Hershey ruled out simply placing an Oreo on top of a Reese's cup -- the two discs didn't perfectly align.

Instead, Hershey decided to try stuffing its peanut butter cup with Oreo crumbles. Helpfully, Mondelez already sold what it calls "Oreo basecakes, " individual wafers that other food companies can use as an ingredient.

But they posed a new problem. The standard Reese's peanut butter cup is gluten-free, an important selling point for some consumers. Gluten, however, helps bind cookies together. Without it, Hershey's machinery -- typically used for pretzels and nuts -- pulverized Oreo's basecakes into a finely ground dust. They turned Reese's filling a distressing gray, and were too fine to deliver a recognizable crunch.

"You don't just want Oreo dust in there," said Charlie Chappell, Hershey's vice president of innovation and R&D.

So Mondelez collected gluten-free basecakes especially for its counterpart, and Hershey designed new equipment that could break them into larger pieces.

The vanilla code

The cookie crumbs took care of Oreo's cocoa flavor in Reese's peanut butter cups. To reflect Oreo's vanilla-creme filling, Hershey decided to split the cup. A white top half would deliver the vanilla, the bottom half would provide the traditional chocolate.

To get the Reese's top to taste like the center of an Oreo, Hershey sought help from flavor houses, specialist firms that do much of the food industry's R&D work. "There's a lot of different vanilla out there, " Chappell said.

Hershey also turned to Mondelez for vanilla advice. This quickly got tricky, Chappell said, with both companies' food scientists adopting a mutual code in order to guide one another in the right direction without spilling their recipes' proprietary details.

"It would be like 'take a look here,' or 'go explore this...' or 'look at it from this angle,'" Hershey's Chappell said.

It took Hershey nine months of trial and error -- longer than most projects -- to get the ratio right between Reese's four components: chocolate, peanut butter, the Oreo cookie and the top creme layer. The company tried more than 35 different versions of the cup and put them through four rounds of consumer testing before everyone was satisfied, Chappell said.

Getting sticky

Mondelez meanwhile was laboring to balance Reese's telltale peanut butter flavor -- derived from peanuts grown in the American South and roasted in Hershey's factories -- in its Oreo.

The 2014 combo cookie featured a split-screen filling, half Reese's peanut butter, half Oreo vanilla creme. For the new product, Mondelez wanted to devote more of the Oreo's double-stuffed layer to peanut butter, with just a touch of its creme filling mixed in.

The problem: Hershey's peanut butter flavor could easily overpower Oreo's subtler vanilla essence. The fix? Add more Oreo. Mondelez's new cookie includes finely ground Oreo crumbs in its peanut butter filling, Chaclin said, helping boost cocoa's flavor while giving a bigger nod to Reese's than a decade ago.

Peanut butter created other challenges. The ingredient was thick and runny, and risked getting clogged during production. Mondelez food scientists worked in the company's test kitchen to hit on the right consistency -- one where the peanut butter wouldn't slide off cookie wafers or get stuck where it shouldn't. It took the company more than 10 different recipes to nail the Oreo.

"Peanut sauce is sticky business," Chaclin said.

Victory dance

Each company had to sign off on the other's product. The two sides sent cookie and candy prototypes to one another via UPS, and held meetings via Microsoft Teams to offer feedback. Small groups of employees also made product-sampling trips between Hershey, Penn., and Mondelez's North America headquarters in East Hanover, N.J., but entry to each other's R&D labs was off limits, Chappell said.

Executives concealed prototypes in silver foil bags to hide their work from prying eyes, including from company employees who weren't in the loop.

After the last round of consumer testing came back strong, Mondelez employees broke into a victory dance. But the project was still top secret. When Chaclin took the final Oreo product home, he said he stored it in a cabinet and forbade his children from showing it to their friends. "They know the routine," he said.

The results of the snack diplomacy are slated to hit supermarket shelves this fall.

The companies are betting that their new products will be especially appealing to younger consumers who enjoy brand collaborations and favor foods with multiple textures and more complex flavors.

Inside the Oreo, the light brown filling squashed between two chocolate wafers resembles the shade found at the middle of a traditional Reese's cup.

The collaborative cups, meanwhile, feature an even top-to-bottom split between the white Oreo cream and the brown Reese's chocolate, with chunks of Oreo crumble sprinkled within the usual peanut butter filling. Hershey is marketing both traditional and mini-sized cup versions.

"I really want you to close your eyes and say, 'yes, I can tell this is an Oreo and it is also a Reese's," Chaclin said. Confused? That's all right, he said, "because it's both."

(END) Dow Jones Newswires

August 08, 2025 22:00 ET (02:00 GMT)

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