507711655-Opera-Patisserie-Cedric-Grolet-1

Make a croissant dough following the directions on this page, using
1¾ cups (420 g) of water.
For the egg wash
In a bowl, whisk together the egg yolks and cream.
For assembly and baking
Cut the dough into 8 by 2¾-inch (20 by 7-cm) rectangles. Place a
stick of chocolate close to the edge of the base of the rectangle, roll
up about ¾ inch (2 cm), add another stick on top, roll up again ¾
inch (2 cm), and repeat a third time to make the pain au chocolat. Let
rise at 80°F (26°C) for about 1 hour 30 minutes.
Preheat the oven to 350°F (175°C). Place the pains au chocolat on a
baking sheet lined with parchment paper and use a brush to lightly
coat with the egg wash. Bake in the oven for 15 minutes. Remove
from the oven and let cool on a rack.