a chocolate or other fat - containing confectionery material is fed into and extruded from a screw extruder and the temperature of the extruder barrel wall and screw are controlled so that the material advanced through the extruder and the product from the die are non - pourable and so that the product is plastically deformable for a period of time , and in particular , the screw and barrel wall temperatures are controlled so that the screw has a temperature higher than the barrel wall temperature . additionally , the material may be advanced within an extruder barrel wall which is roughened and the diameter of the screw root may increase in and along the direction of material advanced in the extruder .