25 Days of Christmas: Day 13

And today's post is...Favourite Christmas Book
Now I really struggled with today's prompt because I couldn't think I any Christmas books but then I suddenly remembered a book I used to read at primary school about a postman who was sending Christmas Mail and you opened the letters and I remember loving it because it was an 'interactive' book (not really but you could open stuff) I any of you know what boom I'm in about, tell me in the comments what it is called because I can't remember! 
What are your favorite Christmas books? Tell me in the comments below and stay tuned for tomorrow's post! 
Katie May xoxo