9 of the wackiest fast-food items of 2015

If one fast-food dish is good, two fast-food dishes combined into one aaare even better.

Items like Burger King's Halloween Whopper, shown here, and Carl's Jr.'s pepperoni pizza fries sparked considerable buzz this year as the industry waged what Carl's Jr. CMO Brad Haley called "a share battle."

"Fast food, in particular, is a very competitive business, and it's important to not only do new menu items regularly but ones that other people aren't doing," he said.

Click ahead to see nine of fast food's most outrageous offerings this year.

—By Katie Little
First published 30 December 2015

Known for its unlimited salad and breadsticks, Olive Garden took the popular breadsticks one step further with new chicken parmigiana and Italian meatball sandwiches that use breadsticks for buns.

Bacon itself is not an unusual pizza topping, but a bacon crust? That's called innovation at Little Caesars, which sold a pizza wrapped in 3.5 feet of bacon earlier this year.

Half pizza, half summer picnic, this Pizza Hut creation with a crust of 28 bite-sized hot dogs sparked intrigue among diners when it launched in June. Before finally bringing the pizza to the U.S., the Yum Brands unit sold mashups of pizza and hot dogs in Australia, Thailand, the Middle East, the United Kingdom and Canada.

Trying to decide between pizza and fries? Well, some Carl's Jr. and Hardee's locations gave customers an option of both flavors in one over-the-top dish. The restaurants tested loaded fries in select Southern California and Midwest locations. Served with a fork, the fries have pepperoni slices, zesty parmesan, marinara pizza sauce and melted mozzarella cheese.

Roughly a year after first diving into the breakfast arena, Taco Bell launched the biscuit taco. While biscuits at breakfast are not new, the dish's taco shape is unique among big fast food players.

After an April Fool's joke proved to be a big hit, Wayback Burgers decided to take its cricket milkshake nationwide this summer. The Oreo mud pie cricket protein milkshake with Peruvian chocolate-flavored cricket powder was part of a limited-time offering of two protein-packed shakes at the 100-unit chain. The other, a jerky milkshake, included barbeque, maple syrup and hickory spice flavors that comes with one or two Slim Jim sticks, depending on the size ordered.

Nothing says spooky like a black bun. Just in time for Halloween, Burger King brought a black bun, already a hit in Japan, stateside with its Halloween Whopper.

Abroad, buns of the rainbow are more commonplace. This year, KFC China sold sandwiches with black and pink buns while Burger King Japan advertised a red bun and McDonald's in China had a gray one.

It's no secret fast food is a cut-throat business, so when several large chains get together to create one burger it generates attention. In honor of Peace Day, Burger King combined parts of its Whopper with ingredients from Denny's Bacon Slamburger, Wayback's Wayback Classic, Krystal's Cheese Krystal and Giraffas' Brutus during a one-day pop-up in September.

In a country known for its burgers, Carl's Jr.'s claim that it was unveiling the most American burger ever was a bold one.

So what exactly is in this patriotic beef creation?

Try a charbroiled, 100 percent Black Angus beef burger sandwiched between Lays potato chips and a split hot dog.