Put 175 g plain flour, 100 g cold butter cut into small cubes and 25 g icing sugar into a food processor and pulse until the mixture resembles breadcrumbs,
then add an egg yolk and a Tbs cold water. Pulse again until the mixture clumps together, then tip onto a work surface and knead the pastry until it is smooth.
Wrap in cling film and chill for 15 minutes, then roll it out thinly and use to line a 23 cm loose-bottomed tart tin. Line with some kitchen foil, fill with
baking beans and bake blind for 12-15 minutes in a preheated 200°C oven. Remove the baking beans and foil and continue to bake for another 10-12 minutes,
until the pastry shell is golden brown. Set aside to cool while you make the filling. Turn the oven down to 170°C. For the filling, whisk 5 eggs, then add
125 ml double cream, 225 g caster sugar and the juice and zest of 4 lemons. Whisk again until well combined, pour into the cooled pastry shell and bake for
about 30-35 minutes, until just set but still with a wobble in the middle. Leave to cool then remove the tart from the tin, dust with icing sugar just before serving.