Chocolate Chip Cookies – Science Behind it

Chocolate chip cookies is going to be a one long post. If you wish you could directly scroll down to the recipe part. But I have discussed the technicalities, science, tips and tricks used to make these cookies so would recommend you to grab a coffee, tea or ice-cream and learn the science of baking.


Chocolate Chip Cookies is a perfect example of both Chemical and Mechanical Aeration.

Chemical Aeration as the name suggests is a process of mixing air into a substance by means of a chemical agent in order to make the end product palatable and easily digestible. The chemical agent used here is Baking Powder..

Mechanical Aeration is the process of mechanically mixing air into the substance using a whisk or paddle attached to a stand mixer or hand blender.

Both these process incorporate air into the mixture.

The gas produced on reaction of baking powder with the acid will be trapped in these air pockets and held in place by the gluten present in the flour.

This (the gas) will expand on heating (in the oven) thereby increasing the volume, which is then held by the coagulation of the gluten (in the flour) and any other proteins present, making the end product light and digestible.

In layman’s words it means butter whips with sugar (in the process of creaming) to create air pockets.


Did you know the temperature of the eggs should be 23 degree celsius for this Chocolate Chip Cookies?

Also eggs should be added in at least four stages in this Chocolate Chip Cookies recipe or for that in every recipe that calls for addition of eggs.

Do you know why??
Well as discussed when butter whips with sugar it creates air pockets. The eggs sits in this air pockets created.

1.If we add eggs all at once it will collapse the air pockets and will result in curdling of the mixture.

2.And hence it is advised to always cream the butter and sugar well that is until they are light and fluffy in order to avoid curdling the mixture after addition of eggs.

3.This is the same reason why some recipes call for alternating the wet and dry ingredients; a precautionary step to avoid curdling.

And this is also exactly the same reason why recipes call out for Scraping the Bowl in regular intervals.?
If we do not scrape the bowl, then the eggs won’t get enough air pockets formed by butter and will collapse thereby curdling the mixture.

And this process of incorporating warmed eggs in stages until completely mixed to form a light and aerated mixture is known as Emulsification

So what do you do if you find that the mixture is going to curdle even after taking care. Just add a tsp of flour and it will balance out the ratio.


What commodities do we need to make Chocolate Chip Cookies?

The role of Brown sugar is to give a caramalised flavour and colour. You can however use castor sugar instead or do half and half.

Compound chocolate is a cheap alternative available to use on a commercial basis. It is made of vegetable oil sugar and little amount of cocoa butter.

It is very important to have warm eggs and to be specific at 23 degree celsius. The reason for this is that if we use cold eggs in the recipe then the liquid in the egg and fat in the butter will curdle and we will be left with whey.


Before we get into the recipe part it is important to know the steps behind making these Chocolate Chip Cookies or to say any biscuit for that matter.. There are 4 main steps involved in baking these chocolate chip cookies.

Step 1 : Conditioning the butter.
Conditioning is a baking term often used in the industry which means softened. If you place your finger onto the butter and you are able to slide through it easily that is what is called a soft butter. When you leave your butter at room temperature for around an hour or so you would reach to this stage. Remember the butter should be soft to touch and not melted.

Step 2: Creaming
It is very important to cream the butter and sugar until light and creamy. A stage which is distinctly marked by the pale yellow colour achieved after beating well. As said above this step is what adds a lot of air into the mixture making the end product very airy and palatable.

Step 3: Emulsification
Emulsification is combining two ingredients that are difficult to mix under normal condition like oil and water. The two things that we emulsify here is the liquid in the eggs and fat in the butter. And to achieve this we add warmed eggs in stages and beat it up until completely emulsifies with the butter.

Step 4: Addition of dry ingredients
And the final step is to sieve the dry ingredients to get rid of any lumps and fold in gently to get the Clear Batter without over mixing it. Clear batter or clear mixture is another baker’s term which means getting a clear batter at the end that is without any dry flour left out or any lumps of butter seen.


The two basic concept here in making chocolate chip cookies is Caramelisation of sugar that is the sugar melts under hot conditions (in the oven) to a liquid state thereby assisting in the flow and spreading out the cookies.

And Coagulation; that is the gas produced by baking powder on reaction with the acidic agent expand on heating under hot conditions thereby increasing the volume, which is then held by the coagulation of the gluten (in the flour) and any other proteins present, making the end product light and digestible. Coagulation in lay man’s words means the conversion of liquids to a solid or semi-solid state.

Here is the detailed step by step instructions.


In a stand mixer using the paddle attachment, or using your hand mixer; beat together the butter, brown and castor sugar until light and fluffy. The image above shows the creaming process after 5 mins and after 10 mins. It would take atleast 10 minutes in a stand-mixer for the creaming process. Don’t forget to scrape the sides of the bowl every minute or so.

Gradually add eggs a tsp at a time and beat until well mixed. Scrape off the sides before each addition.


Sieve the dry ingredients and fold it into the batter until crumbly; that is when you could still see some flour left in it. Refer the above image.

At this stage add the chocolates and mix until a clear batter is formed. Taking care not to chop your chocolates finely as you will end up with a brown dough whereas we are looking for a paler dough.


Dust your work surface with some flour. Transfer the clear batter onto your work surface and shape it into a log. Move the log onto a parchment paper and resize it to 36 cms. Roll and cover it with the paper and let it chill for atleast 20 mins in the freezer.

Once the dough is hard enough to handle cut it into 12 pieces of 3cms each. Give a round shape to each of the piece and flatten it onto a cookie tray lined with parchment paper.

Batch bake these cookies at 180 degree celsius for 15 minutes until golden brown. Batch baking is a technique wherein we place the cookies in a way that each gets enough room to spread and bake evenly.

4.5 from 2 votes
Chocolate Chip Cookies
Prep Time
45 mins
Total Time
1 hr

Servings: 12 cookies
Author: sushma iyer
  • 125 gms Butter (softened)
  • 95 gms Brown sugar
  • 88 gms Castor sugar
  • 62 gms Egg
  • 4 gms Vanilla extract
  • 212 gms Flour
  • 4 gms Baking powder
  • pinch salt
  • 150 gms Chocolate
  1. Cream butter and sugar until light.

  2. Add warmed eggs until well combined

  3. Sieve dry ingredients and fold into batter until crumbly

  4. Add chopped chocolates and mix until clear

  5. Roll into tube shape and divide into 12 equal portions

  6. Bake at preheated oven at 180° celsius for 15-20 mins

Recipe Notes

To measure eggs break open the egg and whisk until whites and yolks are well combined. And then measure out the required amount using a scale.

Baker’s Notes:
1. Condition your butter
2. Use warmed eggs specifically at 23 degree celsius
3. Do not chop your chocolates finely, or else you will end up with a brown coloured dough whereas we want a pale colour dough.
4. Mix your dough till when you get a clear batter. Do not over mix.
5. The more you handle your dough with bare hands while making the log or giving it a round shape the browner your dough will become because of the warmness of your hands so try not to take too much time while doing this step.
6. Every oven is different so you may take more than 15 mins to bake your cookies. Keep checking your cookies after 15 mins and also remember to turn your pan around after 8 mins
7. Batch bake the cookies to bake evenly.

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science-behind-chocolate-chip-cookies step by step method of baking cookies with amazing food photography and all the tips and tricks

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  1. Betsy says:

    Very well explained.these technique will help us a lot
    Do we have to warm the eggs or can we add room temper.ature eggs

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