Preparation

• First make the pastry. In a bowl, soften the butter with a spatula. In a mixer with a paddle (flat beater) attachment, beat the softened butter, ground almonds (almond meal) and icing (confectioners’) sugar until smooth.
  
  Then add the eggs, one at a time, while beating. Incorporate the flour and salt. Mix the pastry dough until crumbly.
  
  Form the dough into a ball, wrap in clingfilm (plastic wrap) and rest overnight in the refrigerator.
  
  Make the lemon custard. Soften the gelatine in a bowl of cold water for 5 minutes. Zest two of the lemons and squeeze all three. In a bowl, beat the eggs with a fork.
  
  
  Combine the lemon juice, sugar and butter in a pan and bring to the boil. Gradually add the eggs, incorporating with a whisk. Cook over a low heat until the mixture comes to a gentle boil.
  
  
  Pour the mixture into a bowl. Squeeze the gelatine and incorporate. Add the lemon zest. Use an immersion blender to mix well. Put into an airtight container and rest overnight in the refrigerator.
  
  
  Preheat the oven to 175°C/350°F/gas mark 4.
  
  Roll out the pastry dough into a 6-mm/1/4-inch-thick disc. Grease a tart pan with butter and line with the pastry. Bake in the preheated oven for 15 minutes.
  
  
  Make the Italian meringue. Dissolve the sugar into 2 tablespoons of water and the lemon juice in a pan over a low heat.
  
  
  Bring to the boil and cook until the mixture reads 120°C/250°F on a cooking thermometer. If you don’t have a cooking thermometer, put a little of the syrup in a spoon and let one drop fall into a glass of cold water. If it forms a small, soft ball, the syrup is ready.
  
  
  In a grease-free bowl, whisk the egg whites to stiff peaks. Pour the syrup in a thin stream into the meringue while whisking until the mixture cools.
  
  
  Fill the pastry case (shell) with the lemon custard. Use a plastic spatula to cover the tart with meringue, creating a dome in the centre. Caramelise with a chef's blowtorch.
  
  
  Chill in the refrigerator for 1 hour before serving.