An ice cream sundae was a type of sundae, a dessert made with ice cream and a flavored syrup.
In 2369, Deanna Troi planned to treat herself with two ice cream sundaes after she completed the crew evaluation reports. (TNG: "Man of the People")
According to the script for "The Child", Delovian soufflé was described as a "
...twenty-fourth century Enterprise
version of an ice cream sundae