put the flour yeast sugar and salt in a large mixing bowl stir together then add 125 milliliters of lukewarm water and stir to form a pliable dough bring the dough together with your hands knead the dough on the work surface for about 5 minutes until it feels elastic put the dough in a lightly oiled bowl cover with cling film and leave to rise in the fridge for 2 hours until doubled in size put the butter between some greaseproof paper and roll into a rectangle about 1 centimeter thick lightly flour the work surface and roll the dough into a large square about 1 centimeter thick lay the unsalted butter across the center of the dough at a diagonal angle fold the four corners of the dough into the middle of the butter so that the butter is encased make sure your butter is chilled but pliable if it's too cold it will be hard and break the pastry layer as you're trying to create if it's too warm it will ooze out as you roll the dough and make the croissants greasy lightly flour the worktop using a rolling pin gently press the dough to flatten this helps the butter to spread out evenly when rolling roll out the dough to a rectangle about 20 and a half centimeters by 40 and a half centimeters fold the bottom third of the dough into the middle then folds the top third over the top like an envelope neaten the edges by pressing them with a rolling pin to make a neat rectangle wrap the dough in cling film and chill in the fridge for 20 minutes lightly flour the work surface lay out the dough with the sealed edge on the left side like a book roll out to a rectangle about 20 and a half centimeters by 40 and a half centimeters repeat the folding process again neaten the edges and return to the fridge for 20 minutes repeat this process of folding and chilling twice more then wrap the dough in cling film and rest in the fridge for one hour to make neat and equal sized croissants make a template take a piece of cardboard and draw a 10 centimeter line across the bottom making a mark halfway across the line 15 centimeters long from the halfway mark join the three points together to form a triangle cut out the template roll the dough out to a rectangle about five millimeters thick make quarter turns of the dough when rolling to get an even thickness trim the edges to straighten then cut out triangles using the template take a triangle of dough with the long tip pointing away lightly roll over the dough with a rolling pin to flatten slightly gently stretch the bottom of the triangle width ways then roll it up towards the long tip curl the ends around to make the traditional crescent shape put the shaped croissants on a baking sheet lined with greaseproof paper leave to rise covered with lightly oiled cling film for one and a half hours until they have puffed up lightly brush the tops of the croissants with beaten egg then bake at 200 degrees centigrade for 15 to 20 minutes until golden brown transfer to a wire rack to cool slightly and serve warm