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If you’re a fan of cooking/baking shows you will have probably seen them come by: almond tuiles. Pretty, delicate and tasty cookies, but, the special bit is that they’re very flexible when they come out of the oven. You can roll them up, creating a tube, just bend them slightly or shape them in plenty of more complex structures.
Even though the tuiles are crispy when cool, they are very flexible actually when they come out of the oven. Why is that?
Why a hot almond tuile is flexible
Most cookies aren’t crispy when they come out of the oven. Most are still slightly soft and flexible. This is due to various reasons, for one thing, any fat (e.g. butter) will still be liquid.
Also, more of the sugar is dissolved as opposed to crystallized. At higher temperatures, sugar dissolves more easily in moisture, but when cooling down some of this will come out of solution. During cooling more water will evaporate, less water, means more crispy (think of chicken skin).
Last but not least, some of the molecules in the flour will recrystallize. The starch especially will crystallize again to a certain extent.
We wrote about this before more extensively when talking about what happens when cookies cool down.
Despite all these phenomena though, most cookies aren’t flexible enough to shape into tubes or otherwise complicated structures. Tuiles are quite unique in that aspect.
Nice and thin
One important reason as to why hot tuiles are so nice and flexible is of course their thickness, or better said, thinness. The thicker the cookie, the sturdier and less flexible it is. A very thin cookie on the other hand will be more flexible and easier to bend. This doesn’t just go up for cookies, it goes up for books, marzipan rods, etc.
Apart from the thinness, the recipe and batter of an almond tuile make it more flexible as well. At the bottom of this post you can see a recipe for an almond tuile. The almond particles shouldn’t play a huge role in its flexiblity since they just sit in between the other ingredients.
Water doesn’t play big role either since a big part of it should and will evaporate during baking. So it comes down to the sugar, butter and flour. There’s only little flour, this is an advantage, flour is what makes cookies sturdier by holding onto water and thickening the whole batter. The butter will be liquid when hot, so it helps keeping it flexible. And then there’s quite a bit of sugar. A lot of this will recrystallize when cooling down, so it’s flexible when hot and sturdy when cold.
If you’d drastically increased the flour content, your tuiles wouldn’t be as flexible anymore.
Challenges of baking a thin cookie
When you make almond tuiles, you want the end result to be crispy, but you won’t know whether it is until you’ve cooled them down! Until you’ve got your perfect recipe & baking method, that will mean you’ll need to do a little bit of trial and error when baking them. Take them out when you think they’re ready, leave them to cool for a few minutes (luckily they cool down very rapidly) and test whether they’re crispy. If not? No panic, just put them bake in the oven.
You get the right crispiness by evaporating enough moisture from the batter. As long as there still is too much moisture, it will be soft insteaead of crispy. Because of this it is important to ensure you’re batter is the same thickness everywhere. Why? In the thicker regions it will take longer for enough moisture to evaporate than in the thinner bits. As a result, they don’t cook evenly.
This is complicated slightly further by the fact that browning goes faster once a cookie has reached a certain degree of dryness. In other words, if it is too liquid it won’t brown yet (because of the Maillard reaction). This is partly why it takes a while for your cookies to brown. But, if your cookies are thicker on the inside than on the outside, it will mean that the outsides brown faster (as you can see on the photos in the post).