Chocolate Croissants (Pain au Chocolat)

Steps

1. Measure 265 ml whole milk, place 15 ml in the refrigerator for the egg wash, and combine the remaining milk with the water in a small bowl or jug; warm this liquid to 38–43°C (100–110°F), stir in the active dry yeast and a pinch of the granulated sugar until dissolved, and let stand about 10 minutes until the surface is foamy.
2. Place the bread flour, the remaining granulated sugar, and the fine sea salt in a large mixing bowl and whisk until evenly combined so the salt is dispersed through the flour and not in direct contact with the yeast mixture.
3. Cut 50 g from the unsalted butter and allow it to soften to about 20–22°C (68–72°F), keeping the remaining 280 g of butter refrigerated; add the softened butter, one egg, and the foamy yeast mixture to the flour mixture and mix with a dough hook or sturdy spoon until a shaggy dough forms.
4. Knead the dough by machine or by hand on a lightly floured surface for about 8–10 minutes until it feels smooth, elastic, and slightly tacky but not sticky, adding only a dusting of flour if needed to prevent sticking.
5. Shape the dough into a rectangle about 3 cm thick, place it on a tray, cover tightly with plastic wrap, and let it rise at 24–27°C (75–80°F) for about 60 minutes until slightly puffy and relaxed, though not necessarily fully doubled in size.
6. Transfer the covered dough to the refrigerator and chill for about 30 minutes until firm but still pliable; the dough should feel cool and supple rather than stiff when pressed with a fingertip.
7. Prepare the butter block during this chilling time by placing the remaining 280 g cold unsalted butter between two sheets of parchment and pounding or rolling it into an even rectangle about 15 × 20 cm, keeping it cold but pliable around 5–7°C (41–45°F), then refrigerate it on a flat surface until needed.
8. Lightly flour a work surface and roll the chilled dough into a rectangle roughly 30 × 45 cm with even thickness, keeping the edges as straight as possible; place the cold butter block on one half of the dough, leaving a small border, fold the bare half of dough over the butter, and press the edges firmly to seal the butter inside.
9. Roll the butter-enclosed dough gently into a long rectangle about 20 × 60 cm, taking care not to let the butter break through; fold the rectangle into thirds like a letter, creating neat layers, wrap tightly in plastic wrap, and refrigerate for 30 minutes so the butter and dough firm up together.
10. Return the dough to the lightly floured surface, roll it again into a rectangle about 20 × 60 cm with smooth, even layers, fold it into thirds like a letter once more, wrap in plastic, and refrigerate for another 30 minutes to keep the butter cold and the dough relaxed.
11. Roll the dough again into a rectangle about 20 × 60 cm, maintaining an even thickness, fold into thirds like a letter for the final turn, wrap well, and chill for a further 30 minutes so the layers stay distinct and the dough feels cool and flexible.
12. Line two baking sheets with parchment paper, place the chilled laminated dough on a lightly floured surface, and roll it into a large rectangle about 25 × 60 cm with a thickness of about 4–5 mm, trimming the edges with a sharp knife to reveal clean, even layers and prevent compressed sides.
13. Cut the dough rectangle into 12 equal smaller rectangles, each with a short side wide enough to wrap around the chocolate; place a strip or line of dark chocolate near one short edge of each piece so the chocolate sits just inside the border of dough.
14. Roll each piece of dough snugly around its chocolate from the chocolate side toward the opposite short edge to form a tight log, keeping tension on the dough without tearing it, and place each roll seam-side down on the prepared baking sheets with generous space between pieces to allow for expansion.
15. Cover the trays loosely with lightly oiled plastic wrap and let the croissants proof at 24–27°C (75–80°F) for about 90 minutes until noticeably larger, soft and slightly jiggly when the tray is gently shaken, and the layers look a bit separated and airy rather than dense.
16. While the pastries finish proofing, about 20 minutes before baking, preheat the oven to 175°C (350°F) and whisk the remaining egg with the reserved 15 ml cold milk in a small bowl until completely smooth to make an egg wash.
17. Uncover the proofed croissants and gently brush them with a thin, even layer of egg wash, avoiding pooling and taking care not to drag the brush across the cut edges so the laminated layers remain well defined and the surface looks glossy but not soaked.
18. Bake the croissants at 175°C (350°F) for about 18–22 minutes, rotating the trays halfway through baking, until they are fully risen, deeply golden brown all over, crisp at the edges, and the chocolate inside is melted and just beginning to bubble slightly at the exposed ends.
19. Cool the pastries on the baking sheets for about 5 minutes to allow the structure to set, then transfer them carefully to a wire rack and cool for at least 15 minutes more until they feel light, the outer layers sound shatteringly crisp when gently tapped, and the interior is tender and cooked through before serving warm.