Theo Randall’s torta della nonna (lemon custard tart with pine nut topping)

Method

1. To make the pastry: in a large bowl, mix the flour, icing sugar and lemon zest, then add the butter. Using your fingertips, rub the butter into the flour until the mixture resembles breadcrumbs. Still using your fingers, work the egg yolks into the mixture until a dough forms, adding 1 tbsp water if it feels dry. (You can also make the pastry in a food processor, pulsing the mixture until it’s the right consistency.) Form into a smooth round ball, then flatten into a 2cm thick disc. Wrap and chill in the fridge for 20 minutes.
2. Cut off two thirds of the pastry, roll it out on a lightly floured work surface and use to line the tart tin with a small amount of overhang. Re-roll what’s left and any offcuts to make a 28cm lid. Cover both with baking paper and keep in the fridge while you make the filling.
3. Pour the milk into a large pan, add the pared strips of lemon peel and bring to a gentle simmer. Meanwhile, whisk the egg yolks and caster sugar until pale and creamy. Whisk in the vanilla extract and cornflour.
4. Discard the lemon peel from the milk, then slowly whisk it into the egg mixture. Once it’s all whisked in, pour the contents of the bowl back into the pan and set over a low heat. Cook very gently for 10-12 minutes, whisking regularly, until the mixture has thickened. Pour into a wide shallow dish (this will speed up the cooling process).
5. Heat the oven to 160°C fan/gas 4. Once the custard has cooled, spoon it into the chilled tart shell. Put the pastry lid on top and seal the edges as neatly as you can, so the custard is fully encased in the pastry.
6. For the topping, whisk the egg yolk and milk together, then use a pastry brush to liberally brush the top of the pastry lid. Scatter over the pine nuts, then put the tart on a baking tray and bake for 1 hour. Leave to cool for 5 minutes in the tin, then remove from the tin and leave to cool completely on a wire rack.