In the late 1800s, "Blue Laws" in the U.S. prohibited the consumption of alcohol on Sundays, and in some states, even drinking soda was against the law on that day of the week. This is why soda fountains saw a dip in business on Sundays and these businesses had to get creative, leading to the birth of the ice cream sundae.

To make up for lost sales, soda fountains in pharmacies started serving ice cream with chocolate syrup and a cherry on top to liven it up, since it didn’t have a flavorful boost from soda. It's not exactly clear who came up with the idea of the sundae first, and various U.S. towns claim to be the home of this treat.

Two Rivers, Wisconsin claims that pharmacist Edward Berners made the first sundae, while Ithaca, New York claims that Chester C. Platt created it 1892, and Plainfield, Illinois says that pharmacist Charles Sonntag invented the treat. Ithaca has the most evidence, including an 1894 trademark request from Platt for the sundae.

As for the name "sundae," the quirky spelling was possibly a hint to customers that they could enjoy the ice cream any day of the week. On the other hand, the spelling may have been chosen to avoid offending church members and their reverence for the Sabbath, which is the reason why "Blue Laws" were created in the first place.