It sure is, I have one here which for some reason best known only to the makers, has KITCHEN stamped under the glaze on the top!
Small versions of these were, so I was told, intended for use as muff-warmers for ladies when travelling in cold draughty coaches, they'd have one inside their muff to keep their hands warm on the journey, and a larger one on the floor which they could rest their feet on to keep those toasty too.