Lemon Bars

Bake the crust. Set a rack in the centre of the oven and heat it to 180°C. Line a 20 × 20 × 5 cm anodised aluminium tin with a strip of baking paper long enough to climb two opposite sides. Blitz the flour, 60 g icing sugar, 1 g salt, 4 g lemon zest and the diced cold butter in a food processor, using about 12 short bursts, until the mix looks dry and pebbly. Tip the crumbs into the tin, flatten them into a level layer, and bake for about 30 minutes, until the base is firm and only just coloured. You can fill it while it is still hot, or let it cool, wrap it tightly and leave it at room temperature for up to two days.

Cook the filling. In a 3-litre stainless-steel pan, mix the granulated sugar with the whole eggs, yolks, 8 g lemon zest and a pinch of salt, then whisk in the lemon juice. Set the pan over a low flame and stir steadily — a calm stir, not a vigorous whisk — until the pan feels warm, about 3 minutes. Raise the heat a notch to medium-low and keep stirring until the mixture thickens, steams, and a probe reads 77°C, about 8 minutes. Straight away, pass it through a sieve onto the crust, level the surface, and tent with foil. Return the tin to the oven for about 10 minutes, until the filling looks smooth and set. Take off the foil, let the tin come down to room temperature, then cover it again and chill for about an hour, until the filling is cold and firm.

Slice. Run a knife around the edge, lift the slab out on the paper, and cut 16 squares, wiping the blade between cuts. Serve as they are, with a light dusting of icing sugar, or with lemon Chantilly and candied pistachios if you have made them.