In the slow growth restaurant environment, chains have a few options for boosting business: build more locations, generate higher sales at existing ones or develop an offshoot brand.
Several restaurant companies are opting for the third route and testing concepts that offer an additional stream of revenue without cannibalizing the success of their existing locations.
"They ultimately see future growth opportunity either declining or limited so they look for new opportunity in the industry for growth," said Darren Tristano, executive vice president at Technomic, in a phone interview.
"Everyone wants to be a growth chain because valuation is higher," Tristano added.
The concepts can also serve as a test kitchen for restaurants to try out new ideas that could trickle down into their flagship brands.
Several of these chains want to capitalize on the speedy growth of the fast-casual segment, which has eclipsed that of the overall restaurant space.
"Right now, everyone is looking at fast casual," Tristano said. "It's the right price, right quality and right appeal for consumers."
Click ahead to see what restaurants are cooking up to boost growth.
—By CNBC's Katie Little
—Last updated March 4, 2015
Following its rapid expansion into the global coffee market,Starbucks has set its sights on tea in addition to food sales. In late May, the chain expanded its tea bar business to Los Angeles.
Starbucks bought Teavana, a chain of mall stores, in 2012. Since then, it has created the tea bar concept, which it plans to expand in cities across the U.S. and beyond.
As the company continues to expand its main casual dining chain, it is also ramping up growth in Bubba's 33, a sports bar concept. Texas Roadhouse plans to open as many as five locations this year, more than the two Bubba's the chain opened last year.
Jaggers, another Roadhouse concept still in its infancy, opened at the tail-end of last year. The fast food restaurant will open a second location – though CEO Kent Taylor said it is too premature to discuss additional expansion.
The owner of Kentucky Fried Chicken and Taco Bell has developed multiple restaurant concepts relatively recently.
At a conference in December, current Yum Brands CEO Greg Creed likened them to "test labs" for ideas.
"So certainly, the food that we're developing there can find its way back into the three iconic brands (KFC, Taco Bell and Pizza Hut," he said. "And then—look, if one of those concepts happens to be a hit, I mean, it really takes off, then obviously, we would go with the flow."
Super Chix, a restaurant in Arlington, Texas, sells hand-breaded chicken that's been cooked in 100 percent refined peanut oil. The restaurant, which is reminiscent of fast-food chain Chick-fil-A, has a relatively simple menu.
Yum Brands also launched a taco business in Huntington Beach, Calif., called U.S. Taco Co. Don't expect the full Mexican or TexMex gamut here. The fare includes "No nachos, no burritos. Just Tacos," according to its website.
Another concept, Banh Shop, strays from the restaurant giant's current offerings and sells fare inspired by Saigon street food.
Chipotle Mexican Grill is one several companies to enter the fast casual pizza business. In late 2013, the company detailed plans to invest in the customizable pizza category through the newly launched concept Pizzeria Locale. The pizza chain now has three locations and plans to open outside of its home Colorado market.
Meanwhile, its Asian-inspired concept ShopHouse Southeast Asian Kitchen now has nine locations open.
These growth spots reflect a belief at the chain that Chipotle's success isn't rooted in just tacos and burritos but rather its ingredient sourcing, cooking techniques and customer experience.
Known more for its chicken wings, Buffalo Wild Wings hopes to "support long-term sustained growth" with its investments in Mexican food and pizza.
It has a majority investment in Rusty Taco, a fast-casual chain that serves street tacos in Dallas, Denver and Minneapolis/St. Paul.
Buffalo Wild Wings also has a stake in PizzaRev, a build-your-own fast casual pizza restaurant.
This year, Buffalo Wild Wings aims to open five company-owned Rusty Taco and PizzaRev locations and expand further through franchising.
Another entrant in the fast-casual space comes from Rave Restaurant Group, already a player in the pizza market with its Pizza Inn chain. Pie Five Pizza sells pizzas that are ready in less than five minutes.
In 2012, Ruby Tuesday bought the Lime Fresh Mexican chain, a fast casual restaurant whose menu includes customizable nachos and homemade tortilla chips. Ruby Tuesday owned and operated 20 locations and its franchisees operated eight as of its last quarterly report.
While Ruby Tuesday has said it thinks Lime Fresh has significant potential, the concept has lagged behind internal targets, according to its latest annual report.
"We made substantial investments in the Lime Fresh brand during the past three fiscal years, and additional investments may be required in order for us to refine and expand the concept in fiscal 2015 and beyond. We can provide no assurance that these investments will be successful or that additional new restaurant growth will be accepted in the targeted markets," the company said in its latest annual report.
"Artisan for all" is how Sbarro's fast-casual concept Pizza Cucinova markets itself. The privately held company, which sells hand-crafted,wood-fired pizzas, currently has two locations in Columbus, Ohio.
With a handful of restaurants in Colorado, D.C. and Illinois, Burger Works offers a limited Red Robin Gourmet Burgers menu with a fast-casual prototype. The company introduced the concept in 2011 to serve areas where full-sized sizes weren't available, such as downtown locations and stadiums.
"Made for the everyday foodie" is how Venti Tre Modern Italian, Fazoli's fast-casual concept, positions itself. The restaurant sells customizable meals featuring at least 23 (Venti Tre is Italian for 23) ingredients to pick from each day.