Should You Grease A Cookie Sheet?
It is not necessary to grease a cookie sheet unless the recipe specifically calls for it. Most cookie recipes do not require greasing the sheet beforehand. In fact, adding extra fat to the pan can cause cookies to spread more than desired. However, if you are baking especially sticky or greasy cookies, or if your pan is old and rusty, a light coating of non-stick cooking spray or butter may help prevent sticking.