I used to hear that when you finished eating ramen and you should say this as a replacement speech of "thank you". It basically means "It must be tired of you to go around to design and prepare for the meal" which implicitly implied an appreciation
gochisou: "feast"
sama: honorific
deshita: past conjugation of "desu", meaning "is"; thus, "was"
In other words, "[that] was a feast".
from https://jp.indeed.com/career-advice/career-development/thank...