The Harry Potter star has penned new book The Further Tale of Peter Rabbit in honour of the Peter Rabbit series's 110th anniversary.
Speaking to Parade, Thompson admitted that the children's book was a truly challenging project.
"Writing is a much harder discipline," she noted. "It's terribly frustrating and makes me weep, but once you start getting it right, it's hugely pleasurable."
Thompson also revealed that she was inspired by her own childhood love of the Peter Rabbit books.
"They were the first books that were read to me, and I read them to my daughter," she recalled. "I read all the time. My idea of heaven is being on a boat with a big box of books."
Thompson next appears on the big screen in the supernatural-themed film Beautiful Creatures, opening on February 13 in the US and the UK.
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Watch a trailer for Beautiful Creatures below: