Step by step recipe:

1. 2 min.
   Sieve together 150 g flour and 150 g icing sugar.
2. 3 min.
   Add 150 g butter cut into small pieces (left for at least 1 hour at room temperature).
3. 1 min.
   Zest 1 lemon.
4. 1 min.
   Add 70 g lemon juice.
5. 1 min.
   And, lastly, 150 g egg.
6. 5 min.
   Beat with a food mixer until the mixture is evenly mixed.
   
   Preheat the oven to 360°F (180°C).
7. 2 min.
   Pour the mixture into a mould or tin, which you can stand on a baking sheet if you wish.
8. 30 min.
   Bake for about 30 minutes, checking if the cake is cooked after 25 minutes.
9. 1 min.
   Turn out the cake.
   
   Leave to cool before serving.