What ingredient makes a chocolate chip cookie gooey?

Here's why:

* Moisture: Brown sugar contains more moisture than granulated sugar. This extra moisture helps keep the cookie soft and chewy.

* Maillard Reaction: Brown sugar also contains molasses, which contributes to the Maillard reaction. This chemical reaction gives cookies their rich, brown color and delicious flavor, and also promotes a slightly gooey texture.

Other factors that contribute to gooey cookies:

* High butter content: Butter adds moisture and richness, contributing to a gooey texture.

* Less flour: Using less flour results in a chewier cookie.

* Underbaking: Baking for a shorter time will leave the cookie with a softer center.

Remember: The perfect gooey cookie is a matter of personal preference! You can adjust the ingredients and baking time to achieve your desired level of gooeyness.