A kitchen was a room or area where food and beverages were prepared for consumption. Due to the common use of replication technology across the Federation by the 23rd century, few Starfleet vessels, space stations, and other outposts included a fully operating kitchen.
One notable exception is the USS Voyager, which was stranded in the Delta Quadrant in 2371. Due to limited resources, replicator rations were instituted and thus a need for traditionally-prepared foods was created. Neelix, a Talaxian crew member, took this opportunity to convert part of Voyager's mess hall into a kitchen and became the ship's chef. (VOY: "Phage")
A ravenous James T. Kirk expressed his intentions to "locate and raid a kitchen somewhere" after being convinced by a neural neutralizer-operating Helen Noel that he was hungry. (TOS: "Dagger of the Mind")
In civilian use, kitchens can be found in restaurants, such as Sisko's Creole Kitchen by Sisko's father, Joseph on Earth. (DS9: "Homefront", "Paradise Lost", "Image in the Sand", "Shadows and Symbols")
While planning his house to be built in Bajor's Kendra Valley, Sisko was unsure about keeping the kitchen separate or opening it up. Kasidy was in favor of the latter, although Ben thought it better to have it separate to stop people "sticking their fingers in my saucepans". (DS9: "Penumbra")
In a possible deleted scene from the Star Trek: Deep Space Nine episode "The Wire", Sisko revealed that Stolpan, a Romulan who worked in the Federation embassy's kitchen on Romulus, was arrested by the Tal Shiar.