The secret is steam and hundreds of paper-thin layers of dough. Puff pastry starts out as a lean dough of just water and flour. This dough gets rolled, stretched, and folded with a healthy amount of butter again and again until all of those layers are formed. The finished pastry dough looks uniform, but it's actually very thin layers of dough separated by equally thin layers of butter.
In the oven, the water in the layers of dough (and some water in the butter) turns into steam. This steam has just enough force to puff up each thin sheet of dough before evaporating into the oven. What's left behind is a delicate shell of airy pastry. Yum.
By the way, you can also prick the puff pastry all over with a fork before baking. This allows the steam to vent in the oven before puffing the layers, so you end up with compressed, shatteringly crisp sheets instead. This is great for Napoleons and rustic tarts, and is also very yum.
Have you ever made your own puff pastry? We're determined to try it for ourselves this month!
(Image: Emma Christensen)