Waiters changed the name because it was “less likely to cause a stir with guests”, according to The Daily Telegraph.
The suet and dried fruit sponge, which is often served with custard, is a popular item on the special desserts menu at Strangers’ Dining Room in Westminster.
Tory MP Andrea Jenkyns was one of the first people to notice the reported change when she said she was offered a “Spotted Richard” by one server.
“I had to ask twice – just to be sure,” she told the Telegraph.
“They have a traditional desserts section, which changes daily, so I asked what the dessert was and that’s when they said it. I still have no idea why.”
Ms Jenkyns added she had “to bite on my lip to stop myself from laughing”.
Fellow Conservative MP Michael Fabricant could also not believe the reported change.
He wrote on Twitter: “Call a dick a dick, I say!”
A House of Commons spokesperson denied staff had been told to refer to the dessert differently.
They said: “Spotted Dick is one of the many traditional hot puddings we serve in our outlets, and there are no changes to the way it is referred to on menus.”