Make the pastry: pulse flour, cold butter, icing sugar and salt in a food processor until it resembles breadcrumbs. Add the egg and pulse until the dough just comes together. Wrap in cling film and refrigerate for 30 minutes.

Roll out the chilled pastry on a lightly floured surface to 3mm thickness. Carefully line a 23cm fluted tart tin, pressing into the edges. Trim excess pastry and prick the base with a fork. Refrigerate for 15 minutes.

Preheat oven to 180°C. Line the pastry case with baking paper and fill with baking beans. Blind bake for 15 minutes, then remove the beans and paper and bake for a further 10 minutes until golden. Set aside to cool.

Make the lemon curd: whisk together the 4 eggs, caster sugar, lemon juice and lemon zest in a heatproof bowl set over a pan of simmering water.

Stir continuously for 10-12 minutes until the mixture thickens and coats the back of a spoon. Remove from heat and whisk in the cubed butter until melted and smooth.

Stir in the double cream until fully incorporated. Strain the lemon curd through a fine sieve to remove any lumps or zest.

Pour the warm lemon curd into the cooled tart shell. Bake at 150°C for 12-15 minutes until the filling is just set with a slight wobble in the centre.

Allow the tart to cool completely at room temperature, then refrigerate for at least 2 hours until fully set. Dust with icing sugar before serving.