Spread 150 g warm, tempered chocolate (say using excess after making the trees later) on the slab with a palette knife until it’s a couple of millimetres thick and the size of a piece of paper, say 23 × 30 cm. Leave to set for a few minutes. You will get different results if the chocolate is set but not too hard or if it is still a bit soft, both are good – experiment. With the scraper, push the edge of the chocolate sheet hard and evenly, at an angle of about 45 degrees. You may get chocolate cigars, or it make crumple into flakes. If it’s a disaster, melt the chocolate and start again.