Dark chocolate and hazelnut meringue pie

To make the pastry, whizz the hazelnuts in a food processor until finely chopped. Add the flour, cocoa, sugar and a pinch of salt, then blitz again until well combined. Add the butter and pulse until the dough resembles rubble. Add 1-2 tbsp of ice-cold water and pulse again until it comes together into a ball. Cover and chill for 20 minutes.

Beat together the egg yolks, cocoa, cornflour and chocolate hazelnut spread in a medium bowl until smooth and thick. Heat the brown sugar and cream in a medium pan with a pinch of salt, stirring to dissolve the sugar. Once steaming (but not boiling), pour over the egg yolk mixture in a steady stream, whisking constantly, until smooth. Return the custard to the pan. Whisk continually over a low heat for 5-8 minutes or until thickened – it should thickly coat the back of a spoon. Don’t be tempted to turn up the heat, as this can cause the custard to split. Keep whisking to a condensed milk consistency.

Transfer the warm chocolate custard to a clean bowl and stir in the chopped dark chocolate until melted and smooth. Leave to cool at room temperature, covering the surface with baking paper to prevent a skin forming.

Roll out the chilled pastry in between two sheets of baking paper to the thickness of a £1 coin, then use it to line a 23cm-wide fluted tart tin, leaving a little overhanging the edge. Press it well into the base, then prick with a fork and chill for 20 minutes.

Heat the oven to 200C/fan 180C/gas 6 and line the pastry case with a scrunched-up piece of baking paper. Fill with baking beans and bake for 15 minutes, then remove the beans and paper, and bake for another 5-10 minutes or until the pastry looks dry and is cooked through. Leave to cool, then trim the edges with a serrated knife. The pastry will be fairly delicate but will firm up slightly when chilled.

Beat the cooled chocolate custard with a whisk to loosen a little – it will have thickened more during cooling. Pour the custard into the cooled pastry case, leaving a small gap at the top for the meringue (you may have 2-3 tbsp of filling left over depending on how tall the tin is). Smooth the surface with the back of a spoon. Chill for 4 hours until set, or overnight – when pressed lightly, your finger will leave a clear indent.

When the filling is set, make the meringue. Put 3 of the egg whites and the caster sugar in a clean heatproof bowl set over a small pan of simmering water, making sure the water doesn’t touch the base of the bowl (you can keep the remaining egg whites for another recipe). Whisk for 5 minutes until the mixture has thickened and tripled in size – when you rub a little between two fingers, you shouldn’t feel any grains of sugar. Remove from the heat and beat with an electric whisk for 6-7 minutes more to stiff peaks. Remove the tart from the tin, spoon over the meringue and create peaks and swirls with the back of a spoon. Use a kitchen blowtorch to caramelise some of the meringue, or put under a hot grill for a few seconds. Dust some more cocoa over the top and scatter with the toasted hazelnuts to serve.