What You Need to Know
The process relies on maintaining butter at 32–35 °C to keep it pliable yet unmelted, while resting dough at 4 °C between folds to relax gluten. During baking, steam expands the butter crystals and the gluten network, while Maillard reactions brown the crust, producing a layered, airy structure.
The Science
Primary Reaction
Steam expansion of butter crystals and gluten network, Maillard browning of crust