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A CHOCOLATE chip cookie, fresh from the oven, cannot fail to be delicious. You don’t need any scientific knowledge to bake great cookies, but it is illuminating to learn how the ingredients combine to affect the flavour and texture – and how you can tweak the recipe to suit your taste.

Most recipes start with creaming butter and sugar together. This isn’t just about combining the ingredients – it is about getting air into the mixture. If you do this for several minutes with an electric mixer, your cookies will be light instead of dense, and .

It is common to use both white and brown sugars. They don’t just taste different; they have different effects on cookie texture. While caster and granulated sugar are almost pure sucrose, brown sugar contains molasses, a byproduct of sugar refining, which makes it slightly moist and acidic. It also contains some glucose and fructose, which are more hygroscopic than sucrose, meaning they absorb moisture. This means cookies made with only brown sugar won’t be as crisp as those made with white sugar.

The acid in brown sugar reacts with the alkaline baking soda to produce carbon dioxide. Cookies made with only brown sugar and don’t spread as wide.

Next, eggs and vanilla extract are mixed in, followed by flour, baking soda, salt and chocolate. Eggs provide protein and fat, helping create the fudgy texture in the centre of a cookie. They are also the main source of moisture in the dough: the water they contain will hydrate the proteins in flour, allowing them to link up into strands of gluten.

Some bakers recommend letting the dough rest in the fridge for a day. During this time, some of the proteins and starches start to break down into smaller molecules. When baked, these molecules recombine in what’s known as the Maillard reaction, creating a browner crust and improving the cookie’s flavour. In my experience, however, once you start thinking about cookies, waiting a day to eat them isn’t humanly possible.

Place six to eight balls of dough on a parchment-lined baking sheet. In the oven, the butter melts and more of the sugar dissolves, making the cookies spread out. Evaporating water swells the air bubbles in the mixture, and baking soda reacts with the acids in brown sugar. Both of these contribute to the cookies’ expansion. Once the proteins and starches harden, the cookies can’t get any larger.

Bake for 10 to 12 minutes at 180°C (350°F), or until light golden brown. They will still be soft, but as they cool down, some of the dissolved sugar recrystallises, crisping them up. A sprinkle of flaky salt as they come out of the oven improves the flavour.

Sam Wong is assistant news editor and self-appointed chief gourmand at ¿ìè¶ÌÊÓƵ. Follow him @samwong1

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