Heat the cream and salt together until steaming hot then set aside.
120 ml (½ cup) vegan double cream (I use Elmlea), ¼ teaspoon salt
Pour the sugar in an even layer into a medium sized saucepan then gently pour the water on top. Without stirring, cook the sugar over medium heat until it comes to a boil and starts to caramelise. To prevent it from crystallising, use a pastry brush dipped in cold water to brush down any sugar crystals that may form around the edge of the pan.
215 g (1 cup + 1 ½ Tablespoons) caster or granulated sugar, 60 ml (¼ cup) water
Once the sugar begins to turn golden around the sides, gently swirl the pan so that it caramelises evenly. Cook until it is a rich golden amber colour, then immediately remove from the heat and stir in the hot cream. Be careful as it will bubble up violently.
Add the butter and stir until melted. Return the pan to the heat, bring up to the boil and cook, stirring every now and again, until it reaches 117-118℃ (243-245°F) on a candy or probe thermometer.
120 g (½ cup) vegan block butter
Remove from the heat and stir in the vanilla. Allow to cool for 3-5 minutes, stirring often, then pour the caramel over the shortbread. Refrigerate for about 3 hours, until set.
1 teaspoon vanilla extract