In the bowl of the stand mixer whisk together the flour, yeast, sugar and salt, then add the water and milk, knead with the dough hook for 5 minutes, the dough will be sticky. Cover the bowl with a clean towel and let sit at room temperature for approximately 40-60 minutes.
On a lightly floured flat surface punch the dough down and form in to a ball, place in a clean bowl, cover and refrigerate for one hour.

Remove the dough from the fridge and roll into a 9×15 inches (23x40cm) rectangle. Spread the softened butter over 2/3 of the dough (leave a 1/4 inch border around the rectangle). Fold the unbuttered third over meeting in the centre, fold the remaining 1/3 on top Rotate the dough 90 degrees and roll again into the same size rectangle and repeat the fold.

Refrigerate for 30 minutes, then repeat fold and refrigerate and one last time fold and refrigerate for 30 minutes.
Roll into a rectangle 10 1/2 x 7 1/2 inches (27x19cm), trim the edges to make everything even. Cut into triangles, a couple of twists with the trimmed edges.

To form the croissant, cut a slit at the bottom of the triangle, gently stretch the triangle lengthwise and widthwise, roll tightly from the bottom up to the tip, place on a parchment paper lined cookie sheet. For the pain au chocolate,, place on cookie sheet, the extra dough can be twisted and also placed on the cookie sheet.