I made croissants and pain au chocolat about 10 years ago and got an itch recently to give it another go. It's basically an enriched dough, plus a bunch of butter folded in carefully and made into funny shapes, a little like a multi-layered biscuit only leavened with yeast instead of dough - and more layers. My enriched dough was a straight dough (everything mixed together and allowed to rise): milk (300 g), butter (38 g), salt (9 g), sugar (15 g), yeast (instant active, 7 g), and Montana Sapphire unbleached white (500 g) and mixed into a stiff dough with a bread machine. It did it's first rise at room temp for a few hours. Then I rolled it into a 10 x 15" rectangle and that's where the images begin.
Above is the dough rolled out and I'm unwrapping my 300 g of butter prepared about a week ago using my spiffy trick to get the butter into a 10" square.
Recipe for these from Wayne Gisslen.