Make the dough: In a large bowl, mix flour, salt, sugar, and yeast. Gradually add cold water and mix until a dough forms. Knead for 5-7 minutes until smooth. Cover and refrigerate for 1 hour.

Prepare the butter: Place the butter between two sheets of parchment paper. Pound and roll it into a 20cm square. Chill for 20 minutes.

Laminate the dough: Roll the chilled dough into a 30cm square. Place the butter square diagonally in the center. Fold the corners of the dough over the butter to enclose it completely.

Roll and fold: Roll the dough into a long rectangle. Fold it into thirds (like a letter). This is one turn. Chill for 30 minutes. Repeat this process two more times.

Shape the pastries: Roll the dough into a 40x20cm rectangle. Cut into 8 smaller rectangles. Place 2-3 chocolate batons at one end of each rectangle and roll up tightly.

Proof and bake: Place the pastries on a baking sheet, seam side down. Brush with egg wash. Let rise for 1-2 hours until puffy. Bake at 200°C (400°F) for 15-20 minutes until golden brown.