Classic Pain Au Chocolat

In a stand mixer fitted with a dough hook, combine the bread flour, cold water, 140ml cold milk, sugar, salt, yeast, and 50g softened butter. Mix on low speed for 5 minutes until a smooth, extensible dough forms.

Turn the dough out onto a surface, shape it into a 20x20cm square, wrap tightly in plastic wrap, and refrigerate overnight. This allows the gluten to relax and the yeast to slowly ferment, developing flavor.

Place the 250g of cold butter between two sheets of parchment paper. Pound with a rolling pin to soften slightly, then roll it into a neat, even 15x15cm square. Keep it pliable but cold.

Roll the chilled dough into a 15x30cm rectangle. Place the butter block on the bottom half, fold the top half of the dough over to completely encase the butter, and pinch the edges to seal. Roll the enclosed dough into a 20x60cm rectangle.

Perform the first simple fold (letter fold) by folding the top third down and the bottom third up over it. Wrap in plastic wrap and chill in the refrigerator for 30 minutes to firm the butter and relax the dough.

Turn the dough 90 degrees so the open seam faces you. Roll it out again to 20x60cm and perform a second simple fold. Chill for another 30 minutes, then repeat this process for a third and final simple fold. Chill for at least 1 hour after the final fold.

Roll the fully chilled laminated dough on a lightly floured surface to a 25x35cm rectangle, about 4mm thick. Using a sharp knife, trim the edges straight to expose the layers, then cut into 12 smaller rectangles (approx 8x15cm each).

Place one chocolate baton at the short edge of a dough rectangle. Fold the dough tightly over the baton, place a second baton snugly against the roll, and continue rolling the dough up. Place seam-side down on a parchment-lined baking sheet.

Proof the pastries in a draft-free environment at 26C/79F for 2 hours. They are ready when they have nearly doubled in size, the layers are distinctly separated, and they jiggle slightly when the baking sheet is shaken.

Whisk the egg and 15ml of milk together. Gently brush this egg wash over the tops of the proofed pastries, being extremely careful not to paint the cut edges, which would glue the layers together and prevent them from rising.

Bake in a preheated oven at 200C/400F for 15 to 18 minutes until deeply golden brown and puffed. The internal temperature of the dough should reach 90C/195F.

Transfer the baked pastries immediately to a wire cooling rack. Allow them to cool for at least 30 minutes before serving so the butter can fully set and the internal steam subsides.