There are thousands of chocolate chip cookie recipes online. Each recipe claims to be the “best” or the “perfect” cookie. But how do bakers know which one is truly the best? It comes down to the science behind the cookie. Although they are a simple dessert, chocolate chip cookies are brought to life by a complicated chemical reaction. In addition to the eponymous chocolate chips, every recipe should include sugar, fat, flour, a rising agent, and a binding agent. Each ingredient plays a specific role in the baking process, and it is important to understand what that role is.
Most chocolate chip cookie recipes start off with sugar. Bakers use two kinds of sugar: white granulated sugar and brown sugar. Brown sugar has the same base as white granulated sugar—the only difference is that brown sugar also contains molasses. Thanks to the molasses, brown sugar gives chocolate chip cookies a softer, chewier texture than white granulated sugar. As a rule of thumb, the darker the sugar, the moister the cookies will be. Dark brown sugar contains approximately double the molasses content as light brown sugar. The added molasses in dark brown sugar will result in the moistest cookies but will also give the cookies an underlying molasses flavor. For this reason, most bakers prefer light brown sugar to dark brown sugar.
Most recipes then call for the sugar to be creamed with a fat. The fat affects the texture and flavor of the cookies. Adding more fat means the cookie will be chewier and more tender. Adding less fat means the cookie will be crispier. The most common fat used in chocolate chip cookies is room-temperature butter. Room-temperature butter contains the perfect amount of moisture to allow the cookies to spread without becoming too thin. Butter also adds a tried-and-true flavor. Bakers can also experiment with other fats, such as browned butter, shortening, or margarine for different textures and flavor undertones.
After the sugar and fat are combined, many recipes call for the introduction of flour. There are many kinds of flour, ranging from varieties with around 8% protein to 14% protein. Flour with a high protein content will produce more gluten during the baking process, resulting in a chewy texture. Flour with a low protein content will result in cakey cookies. The most common flour used to bake cookies is all-purpose flour. All-purpose flour has approximately an 11% protein content, making it a good, “middle-of-the-road” choice for many bakers. All-purpose flour gives cookies enough structure to hold their shape but will still allow for a semi-soft texture. Cake flour (7-9% protein) will result in a soft, fluffy cookie. Bread flour (12-14% protein) produces a larger amount of gluten, resulting in chewy cookies.
Once the flour has been incorporated into the dough, it’s time to add wet ingredients. Chocolate chip cookies only contain a few wet ingredients: eggs, milk, and perhaps a splash of vanilla extract. The primary role of vanilla extract is to enhance the flavor of the cookies. Eggs and milk are commonly referred to as binding agents, and their primary role is to impact the texture of the cookies. Binding agents give the cookies structure while softening the dry ingredients. Bakers should try to find a “happy medium” with binding agents. Adding too many liquids will result in runny batter, but adding too few will result in crumbly, dry batter.
At this point in the process, the dough is almost finished, but there is still a crucial ingredient left: the rising agent. Rising agents react with the other ingredients to produce carbon dioxide bubbles, which lift the cookies. Recipes use baking powder or baking soda as the rising agent. Baking soda needs to react with an acid to create carbon dioxide, so it should be used in recipes with an acidic ingredient like buttermilk or cream of tartar. Baking powder already contains acid, so it is commonly used when a recipe doesn’t have any other acidic ingredients.
After the base of the dough is complete, bakers should add the one non-negotiable ingredient: chocolate chips. Bakers should bake their cookies at approximately 350 – 375 degrees Fahrenheit until the cookies look slightly underdone. Baking times and temperatures vary depending on the recipe, because, as always, there’s a lot of room for variation. Once they understand the ins and outs of baking chocolate chip cookies, bakers no longer need to blindly follow recipes, hoping for the best. Understanding the science behind baking a chocolate chip cookie gives every baker the freedom to find their own perfect recipe.