Insulated Cookie Sheets

In my post "Calibrating My Cookie Sheets - Step 1" from January 10, 2010, I described an experiment in which I baked the same cookie recipe on my six different cookie pans, and for each pan found a "standard cookie" that was slightly browned around the edges. The idea was that if two cookies look the same, then they are baked an equal amount. The results from that experiment will be useful, but today I will expose the flaw in my reasoning for all the world to see, and along the way show why insulated cookie pans may be worth the extra expense if you are dedicated to making wonderful cookies.

Listing the pans I tested again:

1) cheap 13 x 9 Good Cook traditional finish
2) large 15 x 14 Good Cook slide-off pan
3) medium 13 x 12 Good Cook slide-off pan
4) steel 15 x 14 insulated pan
5) aluminum 15 x 14 insulated pan
6) medium 15.25 x 10.25 Wilton pan

The picture I've attached to this post has three rows of cookies. The top row shows one of the "standard cookies" from each pan in the same order, left to right, as they are listed above - but the bottoms are displayed, instead of the tops. The tops of the standard cookies all look approximately the same. As you can see, the bottoms look dramatically different. The fourth and fifth cookies from the left have fairly light bottoms. Three have very dark bottoms, and the left-most cookie has an intermediate shade of brown.

The two cookies with light bottoms were baked on the two insulated pans. The tops are not showing in this picture, but the bottoms of those two cookies are barely darker than the tops. The edges of the tops are slightly browned, and the bottoms have that same slightly brown shade.

The three very dark cookies are from the non-stick pans. These pans all have a darker color and are of fairly heavy metal, so they hold a good amount of heat which is transferred directly to the cookies.

The cookie bottom with intermediate browning was from the lightweight silvery traditional surface pan.

"OK," you might say, "the bottoms are browner if you don't use insulated pans, but who cares? It's the tops that people see!" Good point, absolutely! But cookies are first of all food, and so taste is extremely important. We need to ask, "What do they taste like?" And we might want to know what they smell like, too.

It's a wee bit difficult for me to excite your senses of taste and smell across the Internet, so I'll do my best to describe the cookies. First of all, I mentioned yesterday that I think these cookies had too much sugar, so I wouldn't want to eat them. I have to confess, though, that most of the cookies from yesterday's photo are gone now, and not into the garbage. There were all pretty good. I liked the texture, which was very light because of lengthy creaming and slicing after refrigeration. I did notice differences between cookies baked different times, but won't go into the details because I didn't record any observations about that. I was paying attention to the differences between cookies with brown bottoms and light bottoms, though. In the cookies with light bottoms, I only tasted the sugar, butter, and vanilla. In the cookies with brown bottoms, I tasted the sugar, butter and vanilla along with a slight burnt sugar/burnt flour taste, and the burnt taste was the strongest in the cookies with the darkest bottoms. It's not like the cookies with darker bottoms were inedible by any means, but those with the very darkest bottoms did have a distinctly different taste, and the taste of even the ones with only moderate darkness across the bottom subtly reflected the extra baking on the bottoms.

There are two other rows in the photo, which illustrate the same thing slightly differently. The second row shows the top and bottom of distinctly overbaked cookies from one of the non-insulated sheets. The third row shows the same, from one of the insulated sheets. Even when the cookie is overbaked, the insulated cookie sheet doesn't let the bottom get extremely dark, while overbaking using the non-insulated pan makes the bottom even darker - and you can see from the tops of the cookies in the picture that the cookies from the non-insulated pan weren't even as grossly overbaked as the cookies from the insulated pan, but still the bottom was much darker.

Immediately after baking, the cookies with darker bottoms have a distinct burnt smell if I put the bottom right up to my nose. After a couple of days it's a much weaker smell, but I can still faintly detect it. I wonder if the odor of burnt flour and sugar would hang around longer if the cookies were placed in a cookie tin after baking? Since smell is so important to taste, perhaps cookies with darker bottoms also have a stronger hint of burnt taste the same day they are baked.

I want to emphasize that all six of the standard cookies were perfectly good cookies, dark bottoms or not - they were all baked approximately to the endpoint that most people apparently use for butter cookies, possibly just slightly longer. We probably all grew up eating cookies baked on non-insulated pans and didn't get that upset if the bottoms were somewhat dark. We're talking differences in flavor that are relative subtle to our palates here - but it's probably this sort of subtle difference that makes the difference between a good and a great cookie.

The taste of cookies is supposed to - does - reflect the ingredients. When you bake two different kinds of cookie with different ingredients, you want them to taste quite different from each other; otherwise you might as well simply bake twice as much of the same cookie. To the extent that the cookies have the same ingredients, they will taste the same. All cookies with dark bottoms share the ingredients burnt flour and burnt sugar, which both have relatively strong flavors, and so no matter what their recipe was, they are not as unique as they might have been. Thus, in principle, even if you like the flavor of the burnt sugar and flour, the practice of cookie baking is going to define a good cookie as one which has minimal burnt sugar and flour flavor because it maximizes the differences between cookies made with different recipes. That's probably a pretty esoteric concept - it has nothing to do with whether you enjoy the cookie or not! And in that way, it's kind of bizarre. But I bet it's the kind of thing first-class bakers think about. And personally, I don't think the tastes of burnt flour and burnt sugar meld very well with cookies' sweetness. I actually like flan dessert, which has a very similar taste contrast - but in my taste test, I preferred the cookies with lighter bottoms which came from the insulated pans. So - luckily - the esoteric principle of defining a good cookie as one whose taste reflects the uniqueness of its recipe as much as possible is in harmony with making cookies that simply taste good. For me, anyway!

Until I did the taste test I wasn't sold on insulated baking sheets, but I think I am now. It takes longer to bake the cookies on insulated sheets than on non-stick pans, and that's the trade-off. If I am feeling in a hurry I guess I would still consider using a non-stick baking pan that bakes more quickly, but if I'm first trying to make cookies people will love and I have the time, I'd use the insulated baking sheets.

So how does this affect the pan calibration results? Well, those results aren't totally valid because the "standard" cookies from the different pans aren't all exactly alike. The tops are the same, but the bottoms aren't. It turns out you can't perfectly calibrate all the pans against each other. It looks like all the non-stick pans can be clearly calibrated against each other, and the two insulated pans can be calibrated against each other, but that's it.

Still, I always have to bake the cookies to to some specific endpoint. If the endpoint is defined by how the cookies look or feel on top, as is common, then using my pan calibration when I switch pans is the best I can do to assist in baking all the cookies the proper amount as defined by the recipe. If the recipe only gives an amount of time to bake, then I guess I would still apply the calibration results when switching pan types, but after applying the adjustments to the baking time I might also do a test batch with a non-stick pan baked one minute less than the calibration dictates in order to see if the reduction in burnt flavor from the bottom of the cookies is enough of an improvement to counter whatever adverse effect the shorter baking time might have on the rest of the cookie. That's interesting - with non-insulated pans there is a factor in determining when cookies have been baked the optimal amount of time which is not as big a part of the decision when baking using insulated pans. With non-insulated pans, there appears to be an extra compromise that must be made.

My final comment for this post - it appears at this point as though the two insulated baking sheets behave exactly the same, even though one is aluminum and the other is steel. I didn't expect that! But I did hope for it because this way I can use them as a pair when I bake muliple batches of cookies without worrying about changing what I'm doing for each batch. Whew!