CHICAGO — Old favorites are getting new life under the Golden Arches.

Last month, McDonald’s rolled out two new sizes of Big Macs — the Grand Mac and the Mac Jr. — and a few weeks ago, it added to its annual Shamrock Shake offer with four new mint-flavored drinks. Other riffs on menu staples are being offered in regions around the country, including the Sriracha Big Mac, garlic fries and Chicken McGriddles.

The strategy behind the introductions is a smart one if it works, observers say: It allows the world’s largest burger chain to entice new customers and convince old ones to buy more, while keeping costs low and limiting complications in the kitchen.

“If you look at our past, we were probably too focused on leaning on new products,” said Lance Richards, McDonald’s vice president of menu strategy. “Now we’re celebrating the menu items that are uniquely McDonald’s. And we think there are huge opportunities to do more of that across the menu.”

Since CEO Steve Easterbrook took the helm almost two years ago, the company has focused on improving the quality rather than the quantity of its menu items, but bringing more customers in the door has been a challenge.

McDonald’s needs to entice more customers without going out on a limb to create a flashy new menu item that may not sell, said restaurant consultant Dan McGowan.

“A great hostess walks a step to a step-and-a-half in front of the guest. If they get three or four steps ahead, you’ll have people standing around in the middle of the restaurant looking around saying, ‘Where’d she go?,’” McGowan said. “It’s the same thing with the menu. If you are three or four steps ahead, you might lose them.”

Adding too many new menu items can also bog down a kitchen while workers get used to constructing a new sandwich or using new ingredients.

“You don’t want to give employees a whole new binder on how to assemble a sandwich,” McGowan said. “They know how to make a Big Mac.”

Richards said he “likes the idea” of keeping the Grand Mac and Mac Jr. as limited-time offers and bringing them back at a certain point every year as it does with cult favorites like the McRib and Shamrock Shake.

Richards said that McDonald’s will have a balanced approach to menu innovation going forward, trying some new things as customers demand and also adding to already-popular areas of the menu, like chicken sandwiches and breakfast. The burger chain is looking to expand its coffee brews and flavors and put a focus on specialty coffee, he said.