Lemon curd ice cream

Instructions

• Put the eggs, butter, sugar and
  lemon juice and zest in a heavy
  pan, and cook gently over a low
  heat, stirring, until the mixture coats
  the back of a spoon.
• Leave to cool slightly, then whisk in
  the yogurt. Put in a shallow freezer
  container and freeze until set,
  stirring occasionally to break up
  the ice crystals.
• Transfer to the refrigerator
  20 minutes before serving.