MAKES 22 CROISSANTS
Twelve croissants are baked first; the remaining 10 can be frozen. The croissants take at least 10 hours to make from start to finish, but the process can be spread over two days. We strongly encourage using high-protein all-purpose flour, such as King Arthur, and European-style butter (we like Plugrá). If the dough retracts or softens at any point, fold it into thirds, wrap it in plastic, and freeze it for 15 minutes. Do not make these in a room that is warmer than 80 degrees.

WHY THIS RECIPE WORKS:
The layered structure that characterizes croissants is formed through a process called lamination: A relatively lean yeasted dough is wrapped around a block of butter, and then the package is rolled out and folded repeatedly to form paper-thin layers of dough separated by even thinner layers of butter. Due to increasing gluten formation, the dough becomes more difficult to roll with every turn, so we were relieved to find that three turns was sufficient to yield a light pastry made up of hundreds of delicate layers. High-protein all-purpose flour struck the right gluten balance: enough to support all that butter but not so much that we struggled with the dough. Using the right butter was important, too. The higher water content of conventional butter caused it to break up in the dough, which meant that the dough layers stuck together, resulting in less lift. Using higher-fat European butter worked much better and was worth the extra expense. Lastly, giving the dough and butter packet a couple of intense 30-minute chills in the freezer brought the two components to a more comparable consistency, making it easier to maintain distinct layers.

http://www.americastestkitchenfeed.com/bake-it-better/2013/03/secrets-to-making-croissants-2/