Chocolate Chip Cookies

Yields: 18 Servings Difficulty: Easy Prep Time: 24 Hr Cook Time: 20 Mins Total Time: 24 Hr 20 Mins

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Chocolate Chip Cookies and Differing Baking Times

Introduction/Background Information:

Chocolate Chip Cookies are one of the most iconic American desserts. Many individuals have fond memories from their childhoods eating chocolate chip cookies and milk, an infamous combination that some consider to be unrivaled. The recipe we explored is from New York Times Cooking, a reputable site that strives for perfection and authenticity. With those goals in mind, the recipe is very similar to any other chocolate chip cookie recipe with the addition of ever so fancy chocolate “fèves”, a pre-baking sprinkle of salt, and a very sophisticated (mild sarcasm implied) recommendation to cool your cookies on two separate wire racks. To further this trend of tweaking a nearly perfect recipe to achieve a high level of excellence, we explored how changing the baking time would affect the result of the cookies. In doing this, our readers will be able to modify the recipe to suit their desired cookie “doneness”, allowing for a new customizable recipe. Also, in this post, we will address all of the relevant science behind the ingredients and procedures present in this recipe.

Scientific Content:

The recipe starts off calling for two different types of flour: cake flour and bread flour. In general, flour is used to provide structure to the cookie. The gluten and starch that result from flour create a network that will trap CO2 gas and allow for the cookie dough to rise. Bread flour is higher in protein and allows for more gluten to form creating a stronger network to trap more gas. This will result in a more “firm” cookie texture. Cake flour is lower in protein and allows more gas to escape and therefore allows for a softer cookie texture. Having a mix of these two flour types allows for a more balanced product that a cookie strives to be, somewhere between bread and cake.

The recipe also calls for the addition of salt. Salt impacts the taste of the cookies but also adds strength to the gluten formed from the flour, which aids in forming the overall structure and texture of the cookies. In terms of other dry ingredients, both white and brown sugar are listed in the recipe. Sugar will add sweetness to the cookies as well as aid in the Maillard browning reaction that occurs when baking. A major scientific purpose of sugar is that it attracts and traps more moisture in the cookie, leaving a more moist final product. The use of brown sugar in the recipe specifically provides more moisture due to the molasses content. On the topic of molasses, the molasses present in brown sugar is acidic and provides the acid needed for a leavening agent like baking soda to produce CO2 gas. The addition of chocolate chips in the cookies is strictly for flavor, but it is important to mention that they can provide moisture to the finished product as the chocolate contains moisture in it.

The recipe also calls for the use of eggs. Eggs provide structure to the recipe as well as act as an emulsifier. The use of an emulsifier allows for the stability of an emulsion, which specifically allows for fat or water to be properly dispersed into water or fat. Speaking of fat, the recipe calls for the use of unsalted butter. The butter is unsalted due to salt already being listed in the recipe. The use of fats allows for extra tenderness in the final product as the use of fats can promote moisture retention. It is important to note that butter results in increased tenderness primarily due to the limiting effect it has on gluten formation. On the contrary, the water content present in butter allows for gluten formation when reacting with the flour, but as mentioned, the fat present in the butter limits this gluten formation. This combination allows for the right amount of gluten formation needed to properly bake the cookies. Also, the fat and water content present in eggs have a similar effect of facilitating just the right amount of gluten formation and starch gelatinization. The recipe also calls for the use of vanilla extract. Not only does vanilla extract add to the flavor of the cookies, but it also provides extra water content in the cookie dough which aids in determining the right amount of starch gelatinization and gluten formation. 

Finally, the recipe calls for the use of baking powder and baking soda. The primary function of these ingredients is to act as a chemical leavening agent which leads to CO2 formation. This allows the cookies to rise to the desired amount during baking. However, it is important to discuss why two types of leavening agents are used in this recipe. The baking soda is added primarily to affect the taste of the final product. Given sodium bicarbonate is a basic compound, it will help balance out the acidic taste that will be present in the recipe from components like brown sugar or baking powder. Baking soda, because it is alkaline, also aids in the Maillard browning reaction which adds to the overall flavor and appearance of the cookies. Now the use of baking powder primarily helps with leavening. This is because it is “double acting”, or in more simple terms, promotes CO2 gas formation twice. Given baking powder already contains a base (baking soda) and an acid (i.e. cream of tartar), gas bubbles will first form with the addition of a liquid. The second formation of gas occurs while baking when increased heat will cause a second reaction to occur. This property of baking powder is crucial because it serves as the primary source of leaving in the recipe. This second “double-acting” quality allows for cookie dough to sit and be baked at a later time as the heat produced during baking will encourage chemical leaving.

In terms of procedure, the recipe calls for the dry ingredients to be sifted, which ultimately is just to prevent clumps from forming. The recipe also calls for the sugar and butter to be whipped in a mixer, while eggs are added one at a time. This is done to allow for an emulsion to form between the butter and the eggs that act as an emulsifier. The steady mixing and the slow adding of the eggs allow this process the time it needs to stabilize and thicken. The instructions then call for the dry ingredients to be added to the wet mixture, but with the mixer turned to a lower speed. This edition of the dry to the wet ingredients prevents clumping and the speed adjustment prevents overmixing. Overmixing leads to more gluten formation and therefore results in a tougher, chewy texture, which is not what this recipe calls for. The recipe also calls for the chocolate fèves to be added in, and mixing them in a manner that will not break up the pieces. This allows for a more heterogeneous dispersion of the chocolate in the final cookie.

After the ingredients are mixed, the recipe calls for them to be put into a bowl, covered, and refrigerated. Refrigeration of the cookie dough allows it to become more firm and properly hydrated, therefore preventing overspreading when baking. Covering the dough prevents moisture from escaping and helps the finished product be more moist. Once it is time to bake, the recipe says to preheat the oven to 350 degrees Fahrenheit and line a baking tray with parchment paper to prevent the cookies from sticking. The recipe then says to scoop even-sized balls of the dough onto the baking tray, sprinkle the dough balls with salt for taste and make sure all chocolate pieces are submerged in the dough to prevent chocolate bloom and unshapely melting while baking. The recipe then gives a recommended baking time which is discussed in the section below along with our experimented times and the results which were yielded from altering this variable. Finally, the recipe instructs you to cool the cookies twice, on two separate wire racks. This is done to ensure that the radiated heat from the cookies that is transferred into the first rack does not hinder the cooling process. 

As an ending note, the recipe does not list specific utensils needed, but an electric mixer, an oven, measuring tools, and baking sheets are needed to complete this recipe. It does not seem that altering the “type” of tools will impact the end result as long as the instructed processes are carried out to yield the same result


When people think of a perfect treat few things are above a warm, gooey, soft chocolate chip cookie. Whether the recipe has been passed down for generations or it is a recipe from the internet everyone has a recipe that they think creates the perfect chocolate chip cookie. The question we are asking is what would happen if we changed how long we baked the chocolate chip cookie. Would a cookie baked for less time give us a more desirable end product? We can assume that a longer-baked cookie will be harder and darker while a cookie baked for less time will be lighter and softer, but why? We will go over the science behind the recipe and what the length of baking does to the ingredients inside the cookies.

The ingredients of our recipe will remain unchanged but the amount of time we bake each batch of cookies will change. To ensure that the changes only occur due to the duration of the baking all cookies will be baked at the same temperature 350 degrees Fahrenheit. The first batch will be baked for the least amount of time for just 15 minutes. The second batch will act as our control group as the recommended time for baking cookies is 18-20 minutes so we will bake this batch for 19 minutes. The final cookies will be baked for 23 minutes.

When baking the cookies for just 15 minutes we expect to see cookies which are much lighter in color. A brown cookie is the result of a Maillard reaction and the less time that a cookie is under the heat of an oven the less time there is for a Maillard reaction to take place resulting in a cookie that has browned less. These cookies will also be the softest due to the butter melting but since it is being baked for just 15 minutes it will not be baked long enough for the dough to stiffen up due to the heat. The final thing we are expecting to change is the overall size of the cookie and expect these to be the thickest and smallest cookie. Cookies expand in the oven when butter in the dough melts allowing the dough to spread but due to it only being baked for 15 minutes the butter is not given sufficient time to fully melt and the dough is not given enough time to spread.

The cookies baked for 19 minutes will be just like your regular cookie, with perfect browning, size, and gooeyness. Generally, recipes call for cookies to be baked for 18-20 minutes so 19 minutes is the perfect middle ground. It will allow for Maillard reactions to take place for the perfect amount of time leading to a beautiful golden brown cookie. The butter will also have melted fully and the cookie will have expanded to have the desired size and shape allowing for a good mix of chocolate chips in every bite. When first taken out of the oven these cookies will be gooey and will seemingly melt in your mouth. We expect these cookies to be the best of all the cookies we make which should be no surprise and they are being baked for the recommended amount of time.

The final batch will be baked for 23 minutes 4 minutes longer than the recommended amount of time. Due to them being baked for so long these cookies will be the most brown as Maillard reactions have had ample time to take place and brown the cookies. These cookies will also be the driest as most of the moisture will have evaporated in the prolonged baking process. We expect these cookies to be the thinnest but largest cookies as they have had more time to spread than all the others. This will result in a thin, brittle, and dry cookie which is not what you think of when you think of a perfect chocolate chip cookie. We believe that this batch of cookies will be the worst of the three, although they will still be delicious they will dry so we will have to keep a glass of milk close.


0/11 Ingredients
Adjust Servings
    Dry Ingredients
  • Liquid Ingredients
  • Leavening Agents


0/7 Instructions
  • Sift flours, baking soda, baking powder and salt into a bowl. Set aside.
  • Using a mixer fitted with paddle attachment, cream butter and sugars together until very light, about 5 minutes. Add eggs, one at a time, mixing well after each addition. Stir in the vanilla.
  • Reduce speed to low, add dry ingredients and mix until just combined, 5 to 10 seconds. Drop chocolate pieces in and incorporate them without breaking them. Press plastic wrap against dough and refrigerate for 24 to 36 hou
  • Preheat the oven to 350 degrees. Line a baking sheet with parchment paper or a nonstick baking mat. Set aside.
  • Scoop 6 3½-ounce mounds of dough onto baking sheet, making sure to turn horizontally any chocolate pieces that are poking up. Sprinkle lightly with sea salt.
  • Bake until golden brown but still soft: 18 to 20 minutes.
  • Transfer sheet to a wire rack for 10 minutes, then slip cookies onto another rack to cool a bit more.


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