Knead for 4-5 minutes until a rough consistency is obtained. Place it in refrigerator and leave to rest for at least 3 hours. Roll out the dough, place the butter or margarine (at a temperature between 10 an 15°C) in the centre and fold the dough over on itself to completely envelop it. Roll out again and fold it over to form four layers; place in refrigerator for 15 minutes. Repeat the rolling out and folding procedure for a total of two folds of four layers, then leave in a refrigerator for another 15 minutes. Finally roll out to a thickness of about 4-5 millimeters and create stripes of about 20 centimeters. Place two stripes of BARRETTE at a distance of 6 cm from one to another. Sprinkle a little water on the sides and turn them one after another, giving them the shape of a dumpling. Cut into the shape of a pain au chocolat of 9-10 centimeters. Place them on tins and put them in a rising room at 24°C max with relative humidity of about 70%. Grease with egg and bake at 170-190°C for 15-18 minutes.