The sweet treat has been removed from the £2.99 box but is still available in the small (£1.09) and Freddo (£2.99) selection packs.
The British confectionery company, which is owned by Mondelez International, said it wanted “to improve the mix and offer more of a variety for our fans”.
"Cadbury Fudge is still available in our small selection box and Freddo selection box but has been removed from the medium selection box so that we're offering choice between the ranges"
Fudge fans took to social media to express their frustration, with Twitter user Mark Atwood declaring: “Christmas is ruined.”
Nigel Quinlan accused the firm of waging a “war on Christmas” on Twitter, while Sinead Gleeson called for “a revolution against this chocolate tyranny”.
The biscuit-based treat joins Dairy Milk, Crunchie, Dairy Milk Buttons, Double Decker and Wispa in the company’s “best-selling selection box in the UK”.
"OMG, just heard #Cadbury have changed fudge for Oreo dairy milk, what are you thinking? Have you lost your mind @CadburyUK, it’s the best bit ???????????? #BahHumbug — Louisa Wheeler (@xbabygrovex) December 22, 2017
"@CadburyUK Hold on hold on I don't seem to have a fudge in my selection box. Please explain ???? — LEON ABBOTT (@leonabbott) December 22, 2017