Put the chilled butter, flour and salt into a bowl and rub together between your fingers until you create fine breadcrumbs.
Make a well in the breadcrumbs and add the water. First mix with a knife and then bring together with your hands.
Use your hands to form a ball with the dough.
Then wrap the dough in clingfilm and put into the fridge for around 25 minutes.
Then take off the clingfilm and mark a large cross in the middle with a knife. Don't cut any deeper than half way through.
Pull the 4 corners in the centre of the cross away from the middle, making the cross large enough to put the softened butter into.
Add the butter into the centre and then fold the corners back into the middle, so that the butter is covered. The corners should overlap and no butter should be showing. Make sure the butter is not too hard, the butter should be nicely soft.
Roll the pastry away from you on a floured surface.
Roll out into a rectangular shape, about 3 times its original size.
Do not turn pastry over while rolling but lift occasionally to make sure it isn't sticking.