Ingredients

Step by step

1. Start this a day ahead. Juice the lemons into a big bowl, add the sugar; stir until dissolved.
2. Crack the eggs into a separate bowl and whisk lightly to break the yolks. Add the double cream and mix together loosely – but don't overbeat the eggs. Pour the mixture onto the sugar and lemon juice, and mix well. Do not overmix, though; you want a cohesive yet loose mass. Pass the mixture through a fine sieve – do not force it – and set aside to rest overnight in the fridge.
3. For the pastry, mix the flour, butter, sugar and ½ teaspoon salt in the bowl of an electric mixer fitted with a paddle attachment. Add the egg and egg yolk and bring the dough together very quickly. Remove from the bowl, wrap in clingfilm and set aside in the fridge for 4 hours, or overnight, before using.
4. Preheat the oven to 180°C, fan 160°C, gas 4 and lightly grease a deep 23cm tart tin.
5. Remove the pastry from the fridge. If it's been chilled overnight, let it soften for about 30 minutes then roll out on a lightly floured work surface to a thickness of about 5mm and use it to line the tart tin. Leave any excess pastry hanging over the edges of the tin – this will help it to keep its shape, and can be trimmed off after cooking. Leave the case to rest in the fridge or freezer for 40 minutes or until firm.
6. Line the pastry case with baking paper and fill with baking beans. Bake in the oven for 20 minutes. Remove the tart case from the oven, lift out the paper and baking beans, and return the tart case to the oven for 5-7 minutes until the pastry is golden brown. Remove from the oven and brush beaten egg white over the pastry while it's still hot. This will set and help to seal the pastry.
7. Reduce the oven temperature to 150°C, fan 130°C, gas 2. Set the tart case on a tray in the oven, then pour in the lemon mixture after giving it a good stir. Cook for 35-40 minutes, or until it just sets. The middle should wobble like a jelly. Remove from the oven; leave to cool for 3 hours at room temperature.
8. When cool, trim off the excess pastry and carefully remove the tart from the tin. If you have a blow torch, dust with icing sugar and caramelise lightly. If not, leave out this step. Cut into wedges to serve.