Salted caramel chocolate tart

1 For the pastry, mix the flour, cocoa and a pinch of fine sea salt in a large bowl then, with your fingertips, rub in the butter until it resembles fine breadcrumbs (or pulse in a food processor). Add the egg yolk and 2 tbsp cold water; draw together with a table knife. When it starts to clump, bring together with your hands, adding a sprinkle of water to any dry patches. Knead lightly into a smooth rectangle. Wrap and chill for at least 20 minutes.

2 Preheat the oven to 200˚C, gas mark 6. On a lightly floured surface, roll out the pastry to the thickness of a £1 coin and use to line a 14cm x 35cm (or 22cm round) fluted tart tin. Trim the excess, then pinch the sides up to just above the side of the tin. Use a fork to prick holes in the base. Line with baking parchment, fill with baking beans, then blind-bake on a tray for 20 minutes. Remove the parchment and beans; bake for another 10 minutes, until crisp. Set aside to cool, then remove from the tin and transfer to a serving plate.

3 Meanwhile, make the filling. Finely chop the chocolate; set aside. Put the sugar in a heavy-based pan with 3 tbsp water and heat gently. Stir until dissolved, then let the mixture bubble without stirring, swirling the pan every now and then, until it turns a deep amber (2-10 minutes, depending on the heat of your hob). Keep an eye on it; you don’t want it to burn, but an amber colour means a rich caramel flavour. When it is a good shade, carefully add the butter and cream – it will bubble up – and stir over a low heat. The caramel will harden but melt back into a glossy sauce. Take off the heat; stir in the chocolate and salt until melted. Pour into the pastry case; cool for 30 minutes then chill for 1 hour; the filling should set enough to slice, but not so much it’s hard to cut. Sprinkle over the extra sea salt; serve at room temperature.