What does a yolk do for cookie recipe?

Yolks, while not typically used in cookie recipes, can contribute several things when included:

* Richness and Flavor: Yolks provide a richer flavor and a more intense yellow color to cookies. They contribute to a more decadent and satisfying mouthfeel.

* Moisture: While not as hydrating as whole eggs, yolks still contribute some moisture to the dough, which can lead to a chewier texture.

* Emulsification: Yolks act as emulsifiers, helping to bind the fat and water components of the dough, resulting in a more cohesive and stable batter. This can be helpful for cookies that are prone to spreading too much.

* Texture: Yolks can add a slight chewiness to cookies. This is especially noticeable in cookies with a higher fat content.

It's important to note that:

* Too much yolk can lead to a dense and chewy cookie: The added moisture and richness can result in a cookie that is too chewy and doesn't spread properly.

* Yolks can be replaced with other ingredients: For a leaner cookie, you can typically substitute egg whites for yolks, or use alternative ingredients like applesauce or mashed banana for added moisture and binding.

Therefore, while not standard in cookie recipes, yolks can be used to enhance richness, moisture, and texture, but should be used with caution to avoid over-doing it.