A hot fudge sundae was an Earth dessert.
This food was one of the items sold at Pops Candy Store in 1893 San Francisco. (TNG: "Time's Arrow, Part II")
![Food synthesizer, 2270](https://cdn.statically.io/img/static.wikia.nocookie.net/memoryalpha/images/9/91/Food_synthesizer%2C_2270.jpg/revision/latest/scale-to-width-down/180?cb=20061205202602&path-prefix=en)
In Star Trek: Deep Space Nine Companion, Nana Visitor recalled the rock prop she was encased in for DS9: "Heart of Stone", saying it "looked like a big old hot fudge sundae, and my head was the cherry on top."