Custard tart

Method

1. To make the pastry, whizz the 3 egg yolks with the butter in a food processor (or beat in a bowl with a wooden spoon) until light and fluffy. Gradually pulse in the 85g caster sugar, then the lemon zest. Add the flour with a pinch of salt, pulsing until the dough just comes together. Turn the pastry out onto a lightly floured surface and bring it together gently and quickly with your hands (it will be soft). Press into a thick disc, wrap in cling film and chill in the fridge for 1 hour.
2. Roll the chilled pastry out on a lightly floured surface to the thickness of a £1 coin, then use to line a 23cm diameter, 5cm deep loose-bottomed fluted tart tin, pressing the pastry into the top of each flute so it’s secure. Roll the rolling pin over the top of the case to trim away the excess pastry. Chill again for 30 minutes in the fridge, or in the freezer for 10 minutes. Heat the oven to 190°C/fan170°C/gas 5.
3. When the pastry case is firm, line with foil or baking paper, fill to the brim with baking beans or rice and blind bake for 20 minutes. Take out of the oven and remove the beans/ rice and foil/paper. Turn down the oven to 170°C/fan150°C/gas 31⁄2 and cook for another 5-10 minutes until the case is golden and crisp at the crust, and the inside has a sandy texture with no grey patches.
4. Brush the egg white all over the inside of the pastry case, then return to the oven for 3-4 minutes until hardened (this provides a barrier between the pastry and the filling, helping to keep the pastry crisp). Put the tart tin on a baking sheet and set aside. Turn the oven down again to 130°C/fan110°C/gas 1⁄2.
5. To make the filling, mix the 12 egg yolks in a large bowl with the caster sugar until combined, then pour in the whipping cream, stirring all the time. Strain through a fine sieve into a large pan and heat very gently, stirring often, until just blood temperature (put your finger in it – it should feel warm). Strain again into a jug, then pour into the pastry case, popping as many bubbles that form on the surface as you can.
6. Pull out the middle oven shelf, then very carefully lift the baking sheet with the tart on to it. Cover the tart generously with grated nutmeg, then slide back the shelf and bake for 40-45 minutes until the custard is just set with a gentle wobble. 7. Allow to cool completely in the tin, then carefully transfer to a serving plate. Serve immediately.