1. In a large bowl, mix the softened butter and icing sugar to a cream with a wooden spoon then beat in the egg yolk. Add the flour and salt and rub the butter mixture and flour together with your fingers until crumbly.
 
2. Add the egg yolk to the mixture and knead briefly until it forms a firm dough. Wrap in plastic wrap and leave to chill in the fridge for 30 minutes.
 
3. Roll out the pastry until very thin and line the quiche tin allowing a small amount of pastry to overlap the edges. Prick the base of the pastry with a fork and bake at 400°F for 20 minutes.
 
4. Grate the zest from the lemons into a bowl then add the juice from the lemons. Break the eggs into a large bowl and add the caster sugar and mix well. Add the lemon juice, zest and the cream and whisk gently.
 
5. Pour the mixture into the pastry case and bake at 350°F for 25 to 30 minutes until set.
 
6. Sprinkle with a little icing sugar and serve with cream.