- 125g/4½oz plain flour
- 60g/2½oz cornflour
- 60g/2½oz icing sugar
- 125g/4½oz unsalted butter, chilled and cut into cubes
For the salted caramel
- 250g/9oz light soft brown sugar
- 200ml/7fl oz double cream
- 100g/4oz unsalted butter, softened
- 1 tsp crushed sea salt
For the chocolate topping
- 200g/7oz dark chocolate (70% cocoa solids)
Mix together the shortbread ingredients in a food processor – or do it the traditional way: sift the flour, cornflour and icing sugar into a large bowl, add the cubed butter and, using clean fingertips, rub together until a dough forms.
Wrap the dough in clingfilm and rest in the fridge to rest for 1 hour.
Preheat the oven to 170°C, 325°F, Gas 3.
Line the base and sides of a 22cm/9in square tin with foil or baking parchment. Press the rested dough into this, using the back of a spoon to flatten it.
Prick the top of the shortbread all over with a fork and bake in the preheated oven for 40-45 minutes, until lightly browned and starting to come away from the edges of the tin. Leave to cool in the tin for at least 1 hour before you make the caramel.
To make the caramel, put the sugar and cream in a heavybased saucepan and set over a low heat. Heat gently, stirring constantly with a wooden spoon. Once it comes to the boil, add the butter and stir. Bring back to the boil and let it bubble gently for 5 minutes, stirring occasionally.
Remove the caramel from the heat. Add the salt, stir to ensure it’s thoroughly mixed in then, working quickly, pour over the cooled shortbread. Put the tin in the fridge for at least 1 hour to cool and set.
Once the caramel has set, melt the chocolate in a heatproof bowl set over, but not touching, a saucepan of barely simmering water. Remove from the heat and leave to cool.
Pour the melted chocolate over the caramel and spread lightly and evenly with a spatula.
Leave the chocolate to set then lift the shortbread out of the tin, using the baking parchment, and cut into squares with a sharp knife heated in boiling water. These will keep for up to 3 days in the fridge in an airtight container.