In addition to their yearly cookie sales, the Girl Scouts are also responsible for another iconic treat: the s'more! First published in 1927, the s'more recipe has remained a favorite for backyard barbecues, camping trips, or any place where you can safely roast a marshmallow.

Believe it or not, there's a lot of science that goes into this classic dessert. Let's take a look at what makes a s'more so irresistible.

Part 1: The Graham Cracker

It may surprise you to learn that the sweet cracker with the perfect snap was originally created as a healthy biscuit for vegetarians way back in the 1800's. The two flavors that make graham crackers so distinctive are the sweet taste of honey and the hearty flavor of the wheat, kept whole and coarsely grained for a rustic, robust taste. Graham crackers are the perfect balance to sweet marshmallows and smooth chocolate.

Part 2: The Chocolate

An average chocolate bar melts between 86 and 90 degrees Fahrenheit, which means that you can enjoy that delicious melted texture without risking burning your mouth. Chocolate bars get their flavor from a balance of cocoa powder and cocoa butter, both extracted from the cocoa bean. If the cocoa beans are treated with an alkaline solution before being processed, this results in a milder chocolate flavor and a less acidic taste. We call this "Dutch processing," and it's usually very popular in baked goods. However, Hershey chocolate and other chocolate bars are not Dutch processed. This gives the s'more a little bit of a tangy flavor, which again compliments the sweetness of the marshmallow. Chocolate bars are also tempered so that they can retain their shape. Chocolate is heated and then mixed with unmelted chocolate chunks. This combination, along with strict temperature control, creates a stronger structure and allows for the chocolate to set in various molds.

Part 3: The Marshmallow

Marshmallows are one of the oldest confections of all. Hundreds and hundreds of years ago, bakers would mix honey with the roots of a pink and white flower called a marshmallow to create a sweet, fluffy treat. Over time and lots of trials which were probably very delicious, bakers created a method using gelatin, sugar, and corn starch to create a fluffy, puffy candy. Originally, marshmallows were laid out in trays and traditionally square or other cut out shapes. But modern automation created the rounded shape we're all familiar with today.

Part 4: The Fire

When a marshmallow is heated, three things happen. Firstly, the air inside the treat heats and expands, making the marshmallow puff up. Secondly, the gelatin inside the marshmallow begin to melt. This creates the molten, gooey interior of the s'more. Lastly, the sugars on the surface heat up and bubble. This process is called caramelization. The sugar molecules begin to oxidize, changing the flavor and color. Too much oxidization and the sugars start to burn, although a charred marshmallow is preferred by many.

When the cooked marshmallow is placed on the chocolate, heat transfers from the marshmallow and into the chocolate, causing it to melt as well. Now that this marvel of science has been constructed, you're ready to begin testing. Taste testing!