Legend has it that the original English word was pudding (presumably because that was the most common technique used back in the day for making the sweet course)
The about 200-ish years ago, London’s fashionable crowd, the social climbers, and those aspiring to sound more sophisticated, began to use the French term “dessert” (instead of the local “pudding”). Apparently, they believed this demonstrated to others how well-travelled and well-educated they were, and hence, how wealthy they were. Before you know it, most middle-classes and were calling “pudding” “dessert”. The working classes and factory workers continued to call it “pudding”.
However, this backfired big time. Across Europe royal heads were rolling, so in a bid to appear more in touch with the struggles of the common people, the upper classes in England started toning down how they dress and speak, and adopting more English sounding words in a show of both national unity and in a bid to blend in.
By the late 1800’s, all U’s were saying “pudding”, like the working classes. Some middle classes were still saying “dessert”, but not for very long, as they often tend to follow the U’s. So then the middle classes started saying pudding too! Confused? I don’t blame you.
Today, the term “dessert” sounds pretentious because of its origins and because it is assumed that people use it to sound sophisticated.