Fans of the show were invited to visit the Oxford Street store between 11am and 1pm, to witness a team of chocolatiers from company Melt build the structure.
The egg remained in situ until 4pm, offering members of the public the chance to snap a selfie in front of it.
The 55-centimetre structure, which was made entirely of chocolate, weighed in at 15-kilograms and took more than 25 hours to create.
The stunt was designed to promote the release of Game of Thrones: The Complete Fifth Season on Blu-ray and DVD.
Last week also saw Sky Atlantic get in on the Game of Thrones action. The media brand enlisted snow artist Simon Beck to create a mural made of snow in the French alps, to celebrate the new series.
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