In the bowl of a mixer, add the flour, water and salt. Mix with the dough hook until the dough just comes together, but no longer then 2 minutes. The dough will still seem coarse, but it will smooth out later.
Wrap in plastic wrap and let rest in the fridge for a minimum of 30 minutes.
Put the butter on a large sheet of parchment paper and start beating the butter with your rolling pin. When you have your butter square rolled out to about 12cm wide, put it in the fridge for 10 minutes.
Roll out the dough to three times the length of the butter square. Fold the rectangle in thirds, to create a square and seal the ends with the rolling pin.
With the seam closest to you, roll out the dough again to 20 x 60cm. Fold the rectangle in two, bringing the ends into the middle. Then fold it again in half.
Let the dough rest in the fridge for a minimum of 30 minutes, then proceed with another single and double fold. Let rest in the fridge for an additional 30 minutes.