Some cookie recipes call for pans to be lined with parchment; others want silicone mats. Some say grease, or grease and flour the pans. I sometimes call for lining pans with foil! What’s the scoop on all of this?
If convenience were my sole criterion, I’d say that pan liners in general (and parchment liners in specific) are easier and less messy than greasing or greasing and flouring (I detest that kind of mess!). Liners allow you to slide the cookies off of the pan and onto a rack, should you want quicker cooling, or if you need to reuse the sheet pans again in a hurry. In other words, liners mostly eliminate the need for greasing and the need to transfer hot cookies individually from pan to cooling rack while still hot from the oven. But which liner is best and when might you skip the liner altogether? Here’s how I break down the choices.
Assuming you have reasonably good baking sheets (mine are medium-weight aluminum half sheet pans) that are not dark or burnt or so thin that they warp, an ungreased aluminum pan will produce better caramelization and tasty, crispy edges that contrast with soft chewy centers, ideal for most chocolate chip and oatmeal cookies, and any other cookies with a similarly composed dough. You can also bake shortbread or butter cookies on ungreased pans—as long as the dough is not chocolate (a bare pan will scorch the chocolate slightly). Of course, you have to be willing to transfer cookies to a cooling rack one by one when they come out of the oven. But it may be worth it!
PS: One way to test this for yourself would be to line most of your pan with parchment but leave on end of the tray bare. Try a few cookies on the bare pan. See what you think!
Parchment is the best all-around all-purpose pan preparation. It is excellent for almost every cookie except tuiles and lace cookies (see foil and silicone liners, below), and any other cookie that specifically calls for a foil liner instead. Parchment is also a very reasonable second choice for the chocolate chip and oatmeal cookies that I just said are best baked on a bare pan! Parchment is a slight insulator, which means that compensates and corrects too-thin, burnt, dark, or otherwise poor quality cookie sheets. Its insulating properties are not so great that is lengthens baking time or prevents crispy edges, but they are great enough to prevent super chocolaty batters from scorching.
A foil liner will get you the benefits of a bare pan with the convenience of a liner, so you can remove all of the cookies at once or let them cool on the liner in the pan. Foil, sometimes very lightly but thoroughly greased, is my favorite for lace cookies and tuiles and any thin cookie that you want to be very caramelized throughout.
One tip for lacy or thin cookies baked on foil—they are usually easiest to remove from the foil after they are completely cool, so don’t worry if they seem like they are sticking!
These much-touted mats are good for a few cookies, but definitely not best, or even good, for all cookies. They are good and convenient for very thin fragile wafers, tuiles, and lace cookies. Although I have not tried them for shortbread or butter cookies, they are probably ok (so long as the dough or batter is not chocolaty) as well as for any cookie that you want to be the same texture all the way through: either soft and chewy throughout or completely crispy. Silicon is not great for producing a combination of crispy and caramelized on the outside and chewy in the center. Also, silicon is so insulating that it lengthens baking times and may scorch super chocolaty doughs and batters.
Note: Environmental concerns are my only hesitation about paper and foil liners. I try to reuse them as many times as possible.