I've had a broody brown shaver, for the first time ever! This is a breed that has generally had broodiness bred out of it - it is a commercial egg-laying breed, and the artificial incubators do the nesting, thank you very much. Yet sometimes nature crows very loudly, and you get a throwback.
It was very easy to snap her out of it. I blocked her from the nest box for a day by putting in a bucket with a brick in it (she would have pushed away the bucket alone - it needed the weight of the brick. These clucky hens are very persistent! She did plenty of clucking, too). She went back to normal after that one day.
Note her fluffed-up feathers and angry demeanour. She did NOT like her toasty nest box being interfered with by me.
There is a comprehensive post on this blog about broodiness here.