Christmas Pudding Puzzle - Solution

The Puzzle:

Christmas Pudding
Father Christmas spends 364 days of the year as a taster of Christmas puddings (which is why he is so round and jolly). Recently he came across a Magic Pudding.

If you eat some of this pudding, the next thing you say comes out in a magic code.

Father Christmas tried it, liked it, and said:

"IP! IP! IP! XIBU B MPWFMZ QVEEJOH! NFSSZ DISJTUNBT BOE B IBQQZ OFX ZFBS UP ZPV BMM!"

What did he say?

Our Solution:

Go one letter down in the alphabet: "HO! HO! HO! ..."

Now see if you can figure out the rest!
Puzzle Author: Stephen Froggatt

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