Croissant is French for “crescent,” but the pastry doesn’t always match its name. Croissants au beurre, or butter croissants, are often rolled straight, since croissants ordinaire, made with margarine, are required by French law to be turned in like a crescent moon. Use a ruler when cutting the dough to ensure evenly-sized croissants. Be sure to trim away the edges of the dough before measuring and cutting; butter can be unevenly dispersed around the edges, resulting in less-than-flaky results.
Croissants can be frozen at the end of step 3. Freeze, uncovered, until hard, about 2 hours; transfer to a ziplock plastic bag. Thaw overnight on baking sheets, covered tightly with plastic wrap, in the refrigerator. Proceed with step 4.
Croissants bake most evenly on the middle oven rack. If your oven is large enough to accommodate 2 pans side by side, both batches may be baked at once.