If you've spent any time looking at pictures of food on Instagram in the last year, chances are good you've seen pictures of egg waffles, served up in a cardboard container and sometimes stuffed with ice cream. These bubble waffles aren't a new-fangled creation, though. They're actually an old school street snack from Hong Kong, known as gai daan jai. "It’s one of the most popular street snacks in Hong Kong. It’s probably ranked number one," explains David Chan, cofounder of Wowfulls, a New York City-based company that specializes in making these waffles.

No one really knows the exact history of these Hong Kong egg waffles, except that they emerged a some point in the 1950s, but they certainly caught on like wildfire. You can find these egg waffles all over the city, either cooked over a charcoal stove or in an electric waffle iron, which is the more common cooking method these days.

The most obvious difference between a Hong Kong waffle and a Western-style waffle is, of course, the bubble wrap-like pattern. That's all because of the machine, which is molded to include about twenty round divots. "That’s what creates the semi-spherical bubble shape," says Chan. You can get a commercial egg waffle maker on Alibaba, though there's also a less pricey stovetop egg waffle maker from Nordic Ware—and you really need one of these if you actually want to make these at home.

The batter that's cooked in the deeper, round indentations forms those puffed waffle balls, while the batter that's cooked on flat part of the machine is thin and crispy. "It’s quite different in terms of shape and the texture of it is very crispy on the outside and soft and sweet on the inside," says Chan. "That’s a key difference in terms of the texture," as compared to a Belgian waffle.

Making the right batter also helps create this texture, though there's some debate about what's in the recipe for egg waffles. There's usually eggs, flour, milk, and some sort of leavener like baking powder. Lots of recipes use vanilla extract. Others call for condensed milk, to add a bit of thickness to the batter, while others use custard powder to make the waffles taste more egg-y. These sweet waffles don't require maple syrup, either, which makes them much more tenable as a street food that you could realistically eat on-the-go. "Typically eaten, it’s just plain," says Chan. 

But he and his cofounders at Wowfulls are among the folks who are amping up this traditional treat, making it friendly for the Instagram generation. "This snack is not what you'd call 'new,' but we wanted to revolutionize it and introduce it to a broader audience," says Chan. That's why the folks at Wowfulls turned the bubble waffle into a cone and filled it with ice cream. They also offer a green tea- or chocolate-flavored egg waffle, in addition to the original. These, of course, are the aesthetically pleasing egg waffles you've seen online.

There is a simple pleasure in the original, plain egg waffle, though, especially when enjoyed fresh off the griddle and handed to you in a wax paper bag on the sidewalk. And though there may be new flavors and toppings, there's no question that the traditional Hong Kong waffle is here to stay.