Next to a grease fire, there is rarely anything that causes more excitement in a kitchen than homemade chocolate chip cookies being pulled from the oven. From the smell to the soft, chewy texture, they're without peer.

But despite withstanding temperatures of (at least) 350 degrees, the chocolate chips usually remain solid. Why?

First, some apocryphal chocolate chip cookie history: As the legend goes, the treat was something of an accidental discovery, when Kenneth and Ruth Graves Wakefield were running the Toll House Inn near Whitman, Massachusetts in 1930. In the mood to whip up some Chocolate Butter Drop Do cookies, Ruth realized she was out of baker’s chocolate. She opted instead for some semi-sweet chocolate given to her by Andrew Nestlé of the Nestlé company.

Ruth expected the Nestlé chocolate would behave like baker's chocolate, and melt throughout the cookie dough. But it held firm, keeping its shape and producing what we now know as the chocolate chip cookie. The Toll House brand soon became synonymous with the recipe and Nestlé used the name for recipes and on packaging.

By the end of the 1930s, Nestlé was marketing its own pre-chopped, semi-sweet chocolate morsels, and other companies began to jump on the chip bandwagon. Unlike baking chocolate, chocolate chips differ in that they tend to have a lower amount of cocoa butter, which makes them more resistant to heat. Some chips also have stabilizers and emulsifiers like soy lecithin to help them maintain their shape—the chips are essentially engineered to resist attempts to turn them into liquid. Chips like Nestlé's Morsels do, in fact, melt when baked. But because the cookie dough has firmed up around them, the chips retain their shape. After the cookie has cooled, the chocolate solidifies once more, giving the appearance of a chip that has been unaffected by the heat.

While you can melt chocolate chips—a microwave or double boiler are how you'll get the best result—you’re likely to get a thick and tough concoction. Melting chocolate is usually best reserved for fattier varieties that are more likely to turn into a smooth liquid when heated.

As for Ruth Wakefield: While inventing the chocolate chip cookie should have earned her some kind of financial windfall, she was paid only $1 for rights to the Toll House name in 1939. Nestlé did, however, give her a lifetime supply of their heat-resistant chocolate.

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