Ice cream is an ancient Human dessert, and consists of frozen dairy products, including milk, custard, or cream.
When Captain James T. Kirk was introduced to the Joy Machine he dreamed about the first time he had tried various foods including his first bite of apple pie covered with ice cream and his first taste of a hot fudge sundae. (TOS novel: The Joy Machine)
Vanilla ice cream was served at a formal state dinner on the Paragon Colony. (TOS novel: The Rise and Fall of Khan Noonien Singh, Volume 1)
Corazon Kohwangko enjoyed eating large ice cream sundaes with lots of chocolate. (TOS comic: "So Near the Touch")
After taking control of the USS Enterprise in 2266, Lieutenant Kevin Riley decreed that all of the crew would receive portions of ice cream in honor of St. Kevin's Day. (TOS novelization: The Naked Time)
In 2372, Keiko O'Brien prepared an evening meal for her family that consisted of pot roast and broccoli with ice cream for dessert. (DS9 novel: Wrath of the Prophets)
In 2376 Quark suggested to Taran'atar that he might prefer a Slug-o-Cola, although Taran'atar preferred his usual root beer and ice cream. (DS9 novel: Cathedral)
Strawberry ice cream was a favorite of Lieutenant Rebekah Grabowski prior to her assimilation by the Borg. (TNG novel: Greater Than the Sum)