Americans are sweet on nostalgic treats and snackable indulgences, according to a new dessert report from Datassential, a Chicago-based food industry research firm. For restaurant operators and manufacturers, this may mean the next cupcake or Cronut is a hand pie.

“Nostalgic favorites are appealing to that younger millennial consumer, (who is interested in) more classic styles of desserts,” said Jennifer Aranas, project director at Datassential. “Translating that nostalgia of pie into a more snackable option presents an opportunity.”

Consumers are cuckoo for cookies, said Datassential, which revealed more than three-fourths of survey respondents ate one in the past week.

“For consumers, cookies, brownies and bars are very much an afternoon snack item or a mid-morning snack or late-night snack,” Ms. Aranas said. “So, it’s not only the most often reached for, but it’s also the most recently reached for, versus cheesecake, which is not eaten nearly as often.”

Of consumers who reported eating a cookie within the past two weeks, 43% chose chocolate chip, followed by Oreo (21%), oatmeal (14%), peanut butter (12%) and chocolate (8%). On restaurant menus, classic varieties continue to dominate — led by chocolate chip, oatmeal, peanut butter and sugar cookies — but the fastest-growing flavors are toffee, double chocolate, macaron and rugelach, according to Datassential. Also hot are cookies baked and served in cast-iron skillets, which grew 251% on menus over the past year.

The top trending flavors for brownies served in restaurants are cheesecake, white chocolate, nut and hot fudge. For dessert bars, marshmallow, pumpkin, lemon, dark chocolate and crispy rice varieties are rolling out on more menus.

“When we looked at top trending flavors for cakes, the faster trending flavors are spice cake and dark chocolate, which is particularly important in things like Mexican chocolate or items with more premium ingredients,” Ms. Aranas said.

Italian crème cake, bundt cakes and flourless chocolate cakes also are on the rise in restaurants. The most menued varieties, however, are chocolate, carrot cake, lava cake and lemon cake.

“On the cheesecake side, red velvet, crème brulee, berry, key lime are very rapidly trending,” Ms. Aranas said. “In pies and tarts, Oreo, interestingly, and Boston cream were highly trending. And then pumpkin, which is interesting because we actually fielded this before coming into holiday season.

“French silk and chocolate also are rapidly trending on the pie end.”

Buttermilk, too, is a growing descriptor on pie menus — up 96% in the past year — appearing in such options as buttermilk custard, buttermilk chess pie or a la mode with buttermilk ice cream. But the most common pies on menus remain the traditional favorites, led by apple, key lime, pecan and lemon.

“Things like seasonal specials are always really popular all the time, and not necessarily just in the season that they’re in,” Ms. Aranas said. “I think that’s one of those platforms that can really appeal to manufacturers and chains all year round — to offer items that people really love and look forward to during those holiday seasons but more frequently throughout the year.”

Such limited-time items as the strawberry shortcake at California Pizza Kitchen, the pumpkin spice lava cake at LongHorn Steakhouse, and the peppermint brownie cake pop at Starbucks draw diners with seasonal appeal.

Retro flavors, such as s’mores and red velvet, also resonate with consumers. The classic campfire treat has grown on dessert menus by 133% since 2010, featured most often in a traditional format, as well as the flavor for dessert pizzas, cakes and pies.

Healthier options are of growing interest to consumers, too.

“Healthy and better-for-you is highly interesting to consumers, although when we’ve gotten their feedback, it’s primarily been, ‘When we order dessert, we want decadence and indulgence and we really don’t want anything that’s good for you,’” Ms. Aranas said. “They want it to be better for you, but they know it’s not going to be, and when they’re out there spending their money, they really want to spend it on something that’s worthwhile.”

Still, small portions and treats made with ingredients perceived as natural may appeal to the more than half of consumers who indicated a preference for sinless sweets.

“So, it’s not necessarily taking out sugar or fat, but it’s including those things but maybe with a cleaner label or not a lot of artificial ingredients,” Ms. Aranas said. “It still has sugar, but maybe now instead of processed sugar, it might be cane sugar or agave nectar.

“Or smaller portions… Just a small something that makes you feel good about it, but you still get sweet tooth enjoyment.”