Here’s the Sweet Science of Easter Sunday.

Up until 1847, confections and candies were made in loose bits and chunks, and were custom-bagged and sold by weight. But in that year, Joseph Fry of Bristol, UK, discovered that he could use cocoa butter to bind cocoa powder and sugar into a paste that could be formed and hardened into tablets, and packaged and sold in uniform sizes. Thus was born the world’s first chocolate bar.

This early chocolate would have tasted bitter and chalky to us today. But it could be formed into lots of different shapes and incorporate other ingredients and flavorings. Over the next few decades, J.S. Fry and Sons saw huge success by rolling out over 200 different variations of their product.

In 1873, Fry came up with their most ambitious novelty: Easter eggs formed out of chocolate. Each egg was oversized and ornately hand-decorated, so they were intended more as decorations than for individual consumption. But this led to the eventual development, 90 years later, of Fry’s Crème Eggs, filled with yellow and white fondant filling. They were an absolute sensation, and soon became the most popular confection sold in the UK between New Year’s and Easter, with $200MM in annual sales.

By this time, Fry was part of Cadbury, and in 1971, the Fry name was replaced and “Cadbury’s Crème Eggs” were born. They have since spread to countries around the world, and have been rolled out in dozens of flavor and size variations. Cadbury in turn was acquired in 2011 by Kraft, who elected to retain the Cadbury brand name.

(Sadly, however, this marked the end of J.S. Fry and Sons, as the beloved chocolate works in Bristol were closed. In 2013, archivists at Kraft found in their collection the world’s only known remaining Fry’s Crème Egg, from the original 1963 production, still wrapped in its distinct silver foil package. They placed it, understandably, in cold storage.)

But the Fry innovation lives on in Cadbury Crème Eggs. You can get them in pretty much any store, so help yourself, but we suggest you look for the caramel-filled ones.

Happy Easter.