Classic French Chocolate Filled Puff Pastry

In a large bowl, combine the flour, sugar, salt, and yeast. Add the cold water and 20g of cold butter, cut into small pieces. Mix until a shaggy dough forms, then knead lightly for 2-3 minutes until just combined. Wrap in plastic and chill for 30 minutes.

Place the 200g of cold butter between two sheets of parchment paper and flatten into a 15x15 cm square using a rolling pin. Chill until firm but pliable. On a lightly floured surface, roll out the dough into a 30x30 cm square. Place the butter square diagonally in the center of the dough. Fold the corners of the dough over the butter to enclose it completely, pinching the seams to seal.

Roll the dough into a long rectangle, about 20x60 cm. Perform the first 'turn' by folding one-third of the dough over the middle, then the remaining third over that, like a business letter. Wrap tightly and chill for 30 minutes.

Repeat the rolling and folding process two more times, chilling the dough for 30 minutes after each turn. Ensure you rotate the dough 90 degrees each time before rolling to maintain even layers. After the third turn, chill the dough for at least 1 hour, or preferably overnight.

On a lightly floured surface, roll the chilled dough into a rectangle approximately 20x40 cm and 3-4 mm thick. Trim the edges to create a neat rectangle. Cut the dough into 4 equal rectangles (about 10x20 cm each).

Place one chocolate baton at one end of a dough rectangle, roll it once, then place a second baton and continue rolling to fully enclose the chocolate. Pinch the seam to seal. Repeat for all 4 pastries. Place them on a baking sheet lined with parchment paper, seam-side down. Cover loosely and let proof in a warm place for 1.5 to 2 hours, or until visibly puffed.

Preheat your oven to 190°C. In a small bowl, whisk the egg yolk with the milk to create an egg wash. Gently brush the tops of the proofed pain au chocolat with the egg wash. Bake for 16-18 minutes, or until golden brown and puffed. Let cool slightly on a wire rack before serving. Magnifique!