Shake Shack’s custard made with red velvet cake from District bakery CakeLove. (Jeffrey MacMillan/For the Washington Post)

When Shake Shack’s first Washington location opened two years ago in Dupont Circle, Mark Rosati, the company’s culinary director, spent days wandering the city’s bakeries, farmer’s markets and shops.

His goal: to find locally-made desserts that could help customize the eatery’s line up of custards.

Today, those partnerships with local bakeries such as Baked & Wired, Astro Doughnuts and Pollystyle have continued to grow. Most recently, the New York-based burger joint teamed with CakeLove to create a custard with the District bakery’s red velvet cakes.

“It’s been a great way to add some local flavor and personality,” Rosati said. “We want to reflect the communities that we’re in.”

As the local food movement gains popularity and customers seek more novelty items, area restaurants are increasingly looking to join forces with one another to create something new.

Last week, the food truck Pho on Wheels began selling banh mi sandwiches on savory doughnuts from Astro Doughnuts. Early Mountain Vineyards, owned by local investor Steve Case and his wife, Jean, has teamed with Everona Dairy in Rapidan, Va., to produce a line of wine-soaked cheese.

And at Black Restaurant Group, which includes Pearl Dive Oyster Bar in Logan Circle and Addie’s in Rockville, partnerships with Quartermaine Coffee, Rappahannock Oyster Co. and Toby Island Bay Oyster Co. have resulted in proprietary coffee blends and specially grown Chesapeake Bay oysters that are sold exclusively at Jeff Black’s restaurants.

“It’s a no-brainer to offer our customers something they can’t get anywhere else,” MJ Gimbar, the fishmonger for Black Restaurant Group, said. “And working with other businesses in the area builds more of a community.”

Novelties like the cronut — a donut-croissant pastry that caused a frenzy in New York earlier this summer — and the ramen burger, a beef patty sandwiched between ramen noodles, have ratcheted up the competition for the next culinary invention.

“People are more willing to experiment,” said Elliot Spaisman, co-founder of Astro Doughnuts in downtown Washington. “Anything you can do to get their attention and raise their eyebrows is a good thing.”

Coming together

Although large chains such as Whole Foods and Smashburger have made concerted efforts to add local flourishes at every store, many businesses in the area say their partnerships have stemmed more from friendships and chance encounters.

Dave Kostelnik, general manager of Early Mountain Winery in Madison, Va., says he met the owners of Everona Dairy en route to a food festival. They kept in touch, sampled cheese and wine together, and eventually decided to create the Pride of Bacchus, a piedmont cheese that is soaked in the winery’s lees — the slurry leftover after wine has been fermented — for up to six months. The finished product is a wheel of sheep’s milk cheese with wine flavor.

“It really makes a difference when you can tell your customers the story behind your products,” Kostelnik said. “It creates a much deeper connection than you’d normally have.”

Eventually, Kostelnik says he’d like to partner with a local charcutier to create salami made with red wine.

At Astro Doughnuts, Spaisman is coming up with new ideas, too.

“People are experimenting more and more,” he said, adding that he is tinkering with a doughnut-burger mash-up.

“Me, personally, would I want to eat a burger on a doughnut? Not particularly,” he said. “But a lot of people do.”