In the arms race to offer more luxurious offerings to high-spending travelers, Delta Air Lines has started serving a more extensive buffet with hot food in some of its international Sky Club airport lounges.

Atlanta-based Delta in recent months introduced the array of more substantial food in its Sky Clubs on Concourses E and F at Hartsfield-Jackson International Airport, as well as in Terminal 4 at New York’s John F. Kennedy International Airport.

Delta’s move is another example of the sharper lines being drawn between different classes of service, with higher-spending travelers being treated to top-tier amenities, while those paying discount fares get a stripped-down version.

The improved Sky Club food offerings are an initiative launched by Claude Roussel, Delta Sky Club managing director. Roussel joined Delta in 2014 from the food and beverage industry, and spent 15 years working for French luxury hotel chain Sofitel.

Roussel said he was brought in “to continue making sure the Sky Club is a reason to fly.”

A Sky Club membership costs $450 a year. A single visit pass costs $59. Sky Club access is complimentary for  some, including Delta One business class passengers, Diamond Medallion elite frequent fliers and those with platinum American Express credit cards.

The clubs have long offered snacks like cookies, snack mix, Biscoff, drinks and cocktails.

But they have been gradually boosting their food offerings, introducing fresh salad and soup in 2014.

Roussel said Sky Clubs now offer better complimentary liquor and wine, along with the full buffet at the New York and Atlanta international lounges, including things like roasted sweet potatoes, cavatappi with cheddar sauce, barbecue boneless chicken strips and prosciutto-wrapped mozzarella.

Many of the clubs also now have Starbucks self-serve espresso machines.

Delta isn’t the only club to improve its food selection. Also in Hartsfield-Jackson’s international terminal, the independent lounge known as the Club at ATL on Concourse F now allows customers to order from the menu of Ecco.

United Airlines, meanwhile, recently opened a new club on Concourse T. Delta is building a new club on Concourse B.

Airline lounges are “becoming very sophisticated,” Roussel said.

In Atlanta, Delta has 10 Sky Clubs spread across different concourses and gets about 10,000 visits a day to all of those clubs combined, according to Roussel.

One of the efforts for 2016 will be adding more power outlets in Sky Clubs, Roussel said.