The Science Behind Perfect Chocolate Chip Cookies + Recipe


Chocolate chip cookies are a favorite of many but are surprisingly difficult to get just right. The appropriate size, texture, doneness, chocolate distribution and carmely color and flavor are a lot to think about. In this post, we break down the recipe by ingredient and process to help you figure out where you’re going wrong.



Wait. Did you say cookies?

  1. Flour

This recipe calls for the old standby all-purpose flour but this is not the only option. The main difference between different types of flour is protein content which affects gluten formation and, ultimately, the texture of your final product. Bread flour has a higher protein content, leading to more gluten and a chewier cookie. Cake flour has a lower protein content, leading to less gluten and a soft texture. Just think about the difference between bread and cake. No one wants a chewy cake.

Even using all-purpose flour, you can achieve a different texture in your cookie by altering the amount. A flour to butter ratio of 1:1 or less produces a spread out, lace-like cookie. A ratio of 1.3:1 or higher produces tall, dense cookies.

Be sure to properly measure your flour. Mound flour into the measuring cup and then level it with a butter knife. Flour should be sifted AFTER measuring. You may use a sifter or just run a whisk through the flour a few times. Cookies are more forgiving than cakes so a whisk is fine.

leaveners and thickeners

  1. Leaveners

These chemicals help cookies rise. Generally speaking, you would use salt, baking powder and baking soda as a leavener in cookies. It is important to note that baking soda requires some kind of acid to work properly. In this recipe, I use only baking soda which interacts with the acids found in salt and brown sugar. But what is the difference between soda and powder?

Baking soda is sodium bicarbonate, an alkaline powder and a base. When dissolved in liquid (In this case, egg whites.) it quickly breaks down into sodium and carbon dioxide.

Baking powder contains sodium bicarbonate but also contains powdered acids. Once liquid is added, the acid and the base dissolve and react with each other. Most baking powder canisters will say ‘double-acting,’ which means they contain 2 types of powdered acids. One reacts immediately after water is added and one reacts after being heated.

Baking powder produces cakier cookies with smooth tops. Baking soda produces denser cookies with rough tops.

I always bake with unsalted butter but you can use salted butter and omit the salt from the flour mixture.


  1. Butter

Butter makes cookies tender by interfering with the formation of gluten that happens when flour meets liquid. Beating the butter during the creaming process adds air which will help your cookies rise.

The temperature of your butter may be one of the most important factors when it comes to making soft and chewy cookies. Many bakers misunderstand the phrase ‘softened butter.’ This does not mean microwaved butter, melted butter or hot butter. Softened butter should be cool, pliable and bend in the center. It should not give way and melt when you press your finger into it, as in the picture above. Improperly softened butter will not cream as well with your sugars. It will likely also cause your cookies to spread out and be oily.

The best way to soften butter is to cut it into small squares, as pictured above the heading, and allow to sit at room temperature for about 30 minutes.

Cream the butter by itself first using an electric stand or hand mixer. Properly creamed butter should be lighter in color than stick butter and should have a light and fluffy texture. The image to the left shows slightly beaten butter. It is not done yet! The image on the right shows properly creamed butter.

I prefer to use unsalted butter because it gives me more control over the salt content in the recipe.


  1. Sugars

An appropriate mix of brown sugar is also important to the texture of your cookies. I usually use an equal amount of dark brown sugar and granulated sugar. Light brown sugar has less molasses than dark and can be substituted in equal amounts depending on your taste.  You can also play around with the exact ratio of sugars depending on your personal preference. Brown sugar is ‘wetter’ than granulated sugar and using more of it will produce taller, softer cookies. Using more granulated sugar produces thinner, crunchier cookies.


I recommend using at least some brown sugar even if you want a thin, crunchy cookie. Brown sugar contains molasses which lends a caramely flavor to your cookies. You may not notice this when eating a cookie made with brown sugar but you’ll notice the difference without it.


  1. Vanilla

Why do we want vanilla extract in our chocolate chip cookies? Because not every single bit of the cookie will have chocolate flavor. For the chipless bites, it is important to have some kind of flavor burst. Vanilla pairs well with the slightly salted caramel-esque flavor of the plain cookie dough but there are other options. I’ve tried almond, peppermint, orange and a homemade lemon extract and they were all uniquely delicious.

Opinions about pure versus imitation vanilla vary but, for my chocolate chip cookies, I don’t have a preference. I use the real deal for products that relies heavily on vanilla flavoring like a yellow cake, vanilla ice cream or sugar cookies. However, for products like chocolate chip cookies or brownies I find that imitation works just as well. I use 1 tablespoon, as opposed to the typical 1 teaspoon, in this recipe to give an extra punch of vanilla flavor. 1 tablespoon of vanilla extract is the typical sub for 1 vanilla bean in a recipe if that gives you a better idea of how strong the flavor would be. You can always use less vanilla in your cookies without worrying about adding extra liquid or anything like that. Simply lessen the amount of vanilla.


  1. Eggs

Egg whites provide water to the mix, reacting with the flour to form gluten. Egg proteins are very good at trapping air which aids in the rising process. Using more egg whites will produce a taller cookie. Egg yolks offer well-emulsified fat, giving the cookie a fudgier texture. Using more egg yolks will produce a denser, brownie-like cookie.

Eggs should be at room temperature. Adding fridge cold eggs to your creamed mixture will cause it to curdle. Add the eggs one at a time, beating after each addition.


  1. Chocolate

Chocolate comes in many varieties and many forms. First, we’ll discuss the form of the chocolate. Chocolate chips produce the most regularly chocolate-dotted cookies. Purchased chocolate chunks will lead to some layering of the dough creating a slightly flaky cookie with large pools of chocolate. Hand-chopped chocolate produces the least uniform chocolate pockets. Small shavings of chocolate, as well as chunks will be dispersed throughout the dough lending the most intense chocolate flavor.

Now for the flavors… Depending on the mood I’m in, I use either semisweet or bittersweet chocolate chips in cookies. Semisweet chips contain more sugar, less cacao and have a milder flavor, like milk chocolate. Bittersweet chips contain less sugar, more cacao and have a bitier flavor, like dark chocolate. I prefer baking with these varieties because they do not contain milk so they are not as sensitive to heat.

Which reminds me, dark chocolate is also excellent in cookies. When using dark chocolate in cookies, I prefer to buy good quality bar intended for eating out of hand and chopping them into slightly larger than chip sized pieces.

I tend to avoid using milk chocolate in cookies because the heat can do strange things to the fattier chocolate. The same is true for white chocolate. You don’t need to avoid these varieties completely though. Just be careful when using these flavors and try baking at a slightly lower temperature.

  1. Mixing

While beating the wet ingredients (butter, sugars, eggs, vanilla) is necessary for incorporating air, too much kneading is ill-advised. Over-kneading may undo all your hard work, removing air and forming an overabundance of gluten. This produces tough, chewy in a bad way cookies. When combining your wet ingredients with your flour mixture, fold or mix it together until just incorporated. The chocolate chips should be added to the dough in the same way.

Take some time before the long chilling time to enjoy the fruits of your labor.

  1. Chilling

Chilling the dough before baking helps the cookies hold their shape. Instead of a super thin cookie, you’ll end up with a taller, chewy cookie. I generally chill my dough for 1 hour before AND after shaping my cookie balls. Chilling shaped dough balls for 24 hours before baking produces the very best results but even just 1-3 hours works well. After all, that’s a long time to wait for your cookies!

I tend to bake cookies right out of the fridge which leads to less spreading.

Not only does chilling help with the shape of cookies, it also makes for better flavor. All the ingredients have plenty of time to get acquainted.


  1. Shaping

Spring-loaded cookie scoops are a necessity in my kitchen. They come in multiple sizes, are easy on your hands and wrists and form cookie dough balls of a consistent shape and size. Uniform cookies bake more evenly.


  1. Baking

Parchment paper may be one of my favorite things on the planet! I always use it to line baking sheets and dishes. Cookies baked on parchment tend to bake more evenly and they slide right off after baking.

Oven temperature also has an impact on cookie texture. A cooler bake temp produces flatter, wider cookies and a hotter bake temp produces taller, smaller cookies. A cooler oven also bakes the cookies more evenly.

Some bakers prefer to bake cookies one sheet at a time, with the oven rack at the center of the oven. I like to do 2 sheets at once, with the racks one level up or down from the center. I always make sure to rotate my cookie sheets back to front and top to bottom halfway through the bake time.

Cool the cookies on a wire rack to keep them from going soggy.

Always bake cookies on a cool or room temperature cookie sheet, NOT a hot one fresh from the oven.

And, of course, the last step is to enjoy your delicious cookies!


Handle The Heat put together this helpful post using several different methods.



Plus this animated TED video explains the chemistry of the cookie-baking process. Very interesting!

SweetJ’s Perfect Chocolate Chip Cookies

  • Servings: 2 dozen
  • Time: 30 minutes plus 25 hours optimal chilling time
  • Difficulty: easy
  • Print


2 ¼ cups all-purpose flour, sifted

1 teaspoon baking soda

1 teaspoon salt

1 cup unsalted butter, softened

¾ cup granulated sugar

¾ cup dark brown sugar

1 tablespoon pure vanilla extract

2 large eggs

2 cups (12 oz) semisweet chocolate chips


Whisk together flour, baking soda and salt in a medium size bowl.

In a separate large bowl, beat butter until fluffy.

Beat in sugars and vanilla.

Beat in eggs, one at a time.

Fold or gently mix flour into wet ingredients until just incorporated.

Fold or gently mix in chocolate chips.

Chill dough for 24 hours for best results or 2 hours.

Drop by rounded tablespoon onto a parchment-lined baking sheet.

Chill on baking sheet for 1 hour.

Preheat oven to 350° F.

Bake 8-10 minutes or until golden.

Remove to wire rack to cool.



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