Edinburgh Rock

Method

1. Brush a marble slab or a heavy metal baking tray, and the blade of a palette knife, with 1 tsp of sunflower oil. Have a bowl of cold water and a pastry brush beside the hob, and clip a sugar thermometer to a small heavy-based pan.
2. Put 250 g of granulated sugar and 75 ml of water in the pan over a low heat and stir gently with a wooden spoon only until every grain has dissolved and the syrup is clear. Brush any stray crystals down the inside of the pan with the wet brush.
3. Stir in 0.25 tsp of cream of tartar, raise the heat to medium-high and bring to a fast boil. Do not stir again. Boil for about 12 minutes until the thermometer reads 127C, the soft crack stage — a drop in cold water should form threads that bend before they snap.