At the turn of the 19th century, many states had religion-based blue laws, forbidding certain activities on Sundays like dancing and selling liquor, including sodas.

Since ice cream sodas were all the rage during this time, the prohibition began cutting into soda fountains' business. However, one wily druggist figured out a way around this law.

He simply removed the soda from the dessert. Without the soda, the dessert only consisted of syrup and ice cream, making the concoction legal for sale amidst the prohibition.

There are at least two origin stories with this specific detail from Evanston, Illinois, and Cleveland, Ohio, but the former is the best-known version of the sundae's birth.

In both stories, the sundae became popular enough locally to spread to Chicago — and across the country from there, eventually becoming a classic American dessert.

It became one of Marilyn Monroe's favorite foods, and even Julia Child served a version of this treat: a sundae made with ice cream, bourbon, and a sprinkle of instant coffee.