Lemon Custard Slice

2.Put custard powder and 1 cup of the milk in a medium saucepan and whisk until combined. Whisk 
in sugar and remaining milk. Put over a medium-high heat and 
cook, stirring with whisk, for 
5 minutes or until custard is very thick. Remove from heat and stir 
in lemon zest and juice. Return 
to heat and cook for a further 
2 minutes, stirring continuously. Remove from heat. Pour over biscuits in tin. Top with a second layer of 9 biscuits. Refrigerate 
for 2 hours or until set firmly.

3.To make icing, put icing sugar and passionfruit in a bowl and 
stir until smooth. Spoon icing 
over slice. Refrigerate for a further 
1 hour or overnight, if convenient, until icing sets. Using biscuits as a guide, slice into 9 squares to serve.