NYC’s best hot chocolate is in danger.

“Time has come to share a painful truth: City Bakery is about to go through major changes,” reads a two–part Instagram post the landmark pastry-maker shared Thursday. There is “a strong possibility we will close entirely, and soon.”

The shop at 3 W. 18th St. — home of the $2 homemade hot chocolate marshmallow, an annual Hot Chocolate Festival, and what many New Yorkers consider the best cup cocoa in the five boroughs — may shutter before its 29th birthday in a few weeks.

As the post acknowledges, fans may be “shocked” to learn that the family-owned cafe, which opened in 1990 and draws lines and buzz for its treats, is in trouble. But, they write, “The food business is not what it seems”: The eatery, it turns out, is steeped in debt “like quicksand.”

The Post reached out for comment Friday but did not immediately hear back.

It seems the trouble was sparked by City Bakery’s successful but ultimately folded sister shop, Birdbath Green Bakery. The sweets spot — home to Food Network star Molly Yeh’s favorite chocolate-chip cookie — closed in 2018 after expanding to the Upper West Side.

“Birdbath was embraced and grew from Tribeca to Soho to the UWS, but then we had some misses, and the cost was high,” the post explains, adding that a “normal bank loan” a few years ago would have helped to stabilize their finances.

Although City Bakery hopes to remain in business in some capacity, whether through catering or wholesale, a brick-and-mortar operation may be too hard to maintain, the post says.

If they had it their way, they’d continue serving marshmallows for years to come.

“We’re nowhere close to being ready to pack it in,” they write.