NEW YORK — Even as fast-food chains tout their healthy offerings, they're also coming up with fatty new treats to keep customers interested. Case in point: Dunkin' Donuts is adding a doughnut breakfast sandwich to its national menu next week. The sandwich, which comes with fried eggs and bacon between a split glazed doughnut, will become a part of the permanent menu starting June 7, which the chain claims is "National Donut Day." Dunkin' Donuts had tested the sandwich in select stores in eastern Massachusetts in April, creating considerable buzz online. Notably, Dunkin' Donuts says the doughnut sandwich clocks in at 360 calories, less than the 390 calories for the turkey sausage sandwich it recently introduced for people looking to eat better. Dunkin' Donuts has one location in Louisville—on Bardstown Road at Mid City Mall. In a Q&A posted to the Dunkin' Donuts website,the chef who heads the culinary team behind the doughnut sandwich calls it "fun and quirky." "The glazed donut is light and fluffy and gives you just the right amount of sweetness," said Stan Frankenthaler, executive chef and vice president of Global Product Innovation. "Combined with the lightly salted, smoked bacon, the texture and flavors marry together in a wonderful way. It’s a delicious bite of the perfect harmonization of sweet and savory flavors." WFPL's Joseph Lord contributed to this story.