Even though it's a local delicacy, people all across the United States can celebrate National Boston Cream Pie Day on Oct. 23.

The treat has been the official state dessert of Massachusetts since 1996. However, its origins are much earlier than that.

Chef Augustine François Anezin and staff created the Boston Cream Pie at Boston's Parker House Hotel — known now as Omni Parker House — in the 1860s, according to the hotel.

And despite its name, it's not a pie at all. In an interview Omni Parker House historian Susan Wilson gave to The Boston Globe, she explained the cake is called a "pie" because most commercial kitchens at the time had pie pans, not cake tins.

"The terms' pie' and 'cake' were sometimes used interchangeably," she said.

Today, people all across the United States can order the Boston Cream Pie from the hotel.

"It could be manufactured on a large scale," Corby Kummer, the executive director of the food and society policy program at the Aspen Institute, explained during an appearance on Boston Public Radio Monday.

He said the dessert has a long shelf life in part because of almond flour, which stabilizes the dessert, as well as containing less dairy and eggs that would cause the cake to spoil quickly.

Then the whole pie is topped with chocolate.

"Chocolate was a big luxury, so that rather than have a full layer of a chocolate cream ... you just had a tiny layer of very thin ganache at the top, because that could give the appearance of great luxury," he said.

While the availability of chocolate has changed over the years, the recipe has remained true to its origins.

"We've all come to love it: that small amount of chocolate at the top, the sponge cake and the vanilla custard," Kummer added. "It's very simple."

The Omni Parker House celebrated National Boston Cream Pie Day with a public event from 7 to 9 a.m on Monday, Oct. 23. From 3:30 to 6 p.m., you can try Boston cream pie for yourself in the hotel lobby.