Fried Custard Squares

• 750 ml(26 fl oz/3 cups) milk
• 1 long

Put the milk in a heavy-based saucepan and add the lemon rind and vanilla. Bring just to the boil. Meanwhile, whip 2 eggs in a bowl until they are creamy, then whisk in the sugar. Add the flour and whisk to a smooth cream. Just as the milk comes to a rolling boil, whisk a ladleful into the eggs. Whisking constantly, add another ladleful or