After singing “All I Want for Christmas Is You” for 27 years, Mariah Carey would also like something from McDonald’s.

The pop star is partnering with the fast food giant on “the Mariah menu,” 12 days of deals offered through the McDonald’s app from Dec. 13-24, beginning with a Big Mac on Dec. 13 and ending with chocolate chip cookies on Dec. 24.

Pop star promotions were one of the big restaurant trends of 2021.

Here is a look at some things that shaped the dining industry throughout the year.

Music deals

McDonald’s embraced hip-hop and TikTok in a ground-breaking way through its “Famous Orders” campaign.

It began with a partnership with Travis Scott in September 2020 that included a Travis Scott meal — Quarter Pounder with Cheese, fries, barbecue sauce and a Sprite — and tie-in merchandise.

McDonald’s followed up with with Famous Orders for J Balvin and ventured into the K-Pop world with the band BTS. These celebrity meals repackaged foods that were already on McDonald’s menu, sometimes adding special sauce packets as a novelty. The Saweetie Meal, offered in July, include “Saweetie ‘N Sour” sauce for dipping Chicken McNuggets.

  • A cutout of Snoop Dogg greets drive-thru customers at a Raising Cane’s Chicken Fingers restaurant in Redlands. (Photo by Fielding Buck, The Press-Enterprise/SCNG)

  • Mariah Carey is partnering with McDonald’s on a 12-day holiday food promotion and a beanie giveaway to a few lucky online customers. (Photo courtesy of McDonald’s)

  • Rapper Saweetie poses at Nightingale Plaza in Los Angeles. She partnered with McDonald’s this year in its “Famous Orders” campaign. (AP Photo, Chris Pizzello)

  • BTS poses in the press room with the awards for favorite pop duo or group, favorite pop song for “Butter,” and artist of the year at the American Music Awards on Sunday, Nov. 21, 2021, at Microsoft Theater in Los Angeles. (Photo by Jordan Strauss/Invision/AP)

  • McDonald’s released this logo for its partnership with the seven-member band BTS. (Photo courtesy of McDonald’s)

  • Carl’s Jr. introduced a Hand-Breaded Chicken Sandwich and a Chicken & Waffle Breakfast Sandwich in May. (Photo courtesy of CKE Restaurants)

McDonald’s wasn’t alone

Popeyes Louisiana Kitchen banded with rapper Megan Thee Stallion on Megan Thee Stallion Hottie Sauce for its chicken sandwiches and nuggets in October.

Taco Bell appointed Little Nas X as chief impact officer, an honorary title the chain said “would allow him to collaborate on the brand experience from the inside out.”

And Snoop Dogg continued an association with Raising Cane’s Chicken Fingers that included working a drive-thru window at a Dallas restaurant.

Chicken sandwiches

Fried chicken sandwiches have become a must-have on quick service menus. The so-called chicken sandwich wars started in August 2019, when Popeyes Louisiana Chicken added a sandwich to its menu, going up against Chick-fil-A, and in 2021 nobody seemed willing to call a truce.

“Now it’s just required that everyone have a chicken sandwich,” said marketing expert Deb Gabor, author of “Irrational Loyalty,” a book about how companies bond with consumers.

Carl’s Jr. went big on crispy chicken, added sandwiches to its permanent menu and its breakfast menu and then following up with limited time offers. Burger King, McDonald’s and Farmer Boys made similar moves.

Chains that were already known for chicken, such as KFC and Wendy’s, added new chicken sandwiches to their menus.

Jollibee, an Asian restaurant chain that is rapidly growing in the United States, entered the fray in September with its Jollibee Chickenwich and in December introduced Spicy Chickenjoy, a hotter version of its  signature fried chicken.

Virtual brands

With restaurants closed or unable to use all of their space due to lockdown, the novel coronavirus created a growth climate for online brands that are ordered through delivery services. They bring food to the public instead of requiring people to come to them.

Such businesses are called virtual kitchens. Other frequently used terms include ghost kitchens and cloud kitchens. They often have short menus focused on items that travel well, such as chicken wings.

The appeal to entrepreneurs is low startup costs and fewer real estate headaches.

Robert Earl, co-founder of Virtual Dining Concepts, was selected by Quick Service Restaurants magazine as one of the top digital disruptors of 2021. Last last year he hit pay dirt launching Mr. Beast Burger, a partnership with influencer Jimmy Donaldson, who has 62 million YouTube subscribers.

Earl also partnered with celebrity chef Guy Fieri and other stars such as Mariah Carey, whose McDonald’s collaboration includes free cookies, perhaps putting her in competition with her own online cookie business.

One of his newer concepts is Buddy V’s Cake Slice, a partnership with “Cake Boss” star Buddy Valastro that can be ordered in Southern California cities from Encino to Yucaipa, according to its website.

Established restaurant chains are also dabbling in virtual concepts. They include Dickey’s Barbecue Pit, which in June launched a virtual brand called Big Deal Burgers. Cracker Barrel, which has only two locations in the Inland Empire, expanded its footprint into Hollywood through a virtual operation called Cracker Barrel Kitchen.

‘Real’ food

Consumers’ growing awareness of what they’re putting in their bodies has caused several restaurant chains to describe their foods as minimally processed or “real.”

Islands Restaurant, a casual chain, launched a “clean food” campaign last summer, promoting its made-to-order french fries.

In August, Shake Shack boasted about Damon Roy, the New Orleans beekeeper who generated much of the raw honey used in the glaze for the chain’s Hot Honey Chicken sandwich.

Chipotle Mexican Grill, which boasts about the limited number of ingredients in its foods, takes it a step further by campaigning for sustainability. In November, it announced a plan to reduce greenhouse gas emissions 50 percent by 2030 in its supply chain, restaurant operations and packaging.

Chipotle also carries out its real food theme in its online merchandise. This month, it introduced an “all natural” bar of cilantro soap.

Staff shortages

Fallout from the novel coronavirus pandemic continues months after California reopened dining rooms.

Restaurants are striving to make customers’ experiences as normal as possible, but staffing shortages remain a challenge.

Some have responded by shortening their menus, shortening their hours or opening on fewer days.

But the challenge is more than just the number of employees, according to Mike Whatley, vice president for State Affairs and Grassroots Advocacy for the National Restaurant Association.

It’s the loss of experience and even of a friendly face that diners remember.

“We’ve lost a lot of talent, both front of house and back of house,” he said in a phone interview.

“There are a lot of people who go to a restaurant because of their favorite food server or favorite bartender. If that person has left the industry or left that restaurant, that affects customer experience.”