
The internal structure of a croissant comes from lamination.
Bakers repeatedly fold dough around layers of butter, creating many alternating sheets. During baking, water in the butter and dough turns to steam while the fat helps keep layers separated.
The expanding steam pushes those thin layers apart and creates the characteristic flaky interior.
A croissant's structure is essentially built before it ever enters the oven.
© Institute of Culinary Education