Pastry structures (uncooked doughs shown at bottom; cooked pastries at top). The key to pastry structure is the distribution of the fat, here shown as a light layer surrounding darker masses of dough. Left: In crumbly pastries, fat coats and separates small particles of dough. Center: In flaky pastries, fat coats and separates flattened pieces of dough. Right: In laminated pastries, fat coats and separates extended, thin sheets of dough. The sheets in laminated pastries are so light that cooking steams them apart into a light, airy structure.