Cinder toffee

Method
Prep:5min  ›  Cook:15min  ›  Extra time:40min  ›  Ready in:1hr 

1. Grease a 20x30cm tin, then line the bottom and sides with baking parchment, making sure the parchment sides are at least 5cm above the sides of the tin. Grease the parchment with a little butter or oil.
2. Add sugar, golden syrup, vanilla and water to a deep, heavy bottomed saucepan. Bring the mixture to the boil, but do not stir. Boil until it reaches the hard crack stage (the temperature on a sugar thermometer reads 149 - 154 degrees C), about 10 minutes. During boiling, if there are any sugar crystals on the sides of the pan, brush the sides of the pan with a clean pastry brush dipped in water.
3. Remove from heat and working quickly, add the bicarb, whisking to incorporate. The mixture will bubble when adding the bicarb, so mind the hot toffee. Immediately pour into the prepared tin. Let cool and set completely before touching. Break into pieces and serve. Store at room temperature in an airtight container.