No-Bake Lemon Slice

Slice:
half a 415g (13oz) can condensed milk
125g (4oz) butter, melted
250g (8oz) gluten-free cornflakes, crushed
OR 250g (8oz) gluten-free rice cookies, crushed
1/2 cup desiccated coconut
1/2 cup shredded coconut
1 tablespoon lemon juice
grated rind of 1 lemon OR mandarin

Icing:
250g (8oz) pure icing sugar
2 tablespoons butter, melted
2 tablespoons lemon juice
a little hot water

Mix the slice ingredients well. Press into a lightly greased dish.
In a separate bowl, bash the lumps out of the pure icing sugar. Add 2 tablespoons of melted butter and 2 tablespoons of lemon juice. Mix well. Very slowly add a little hot water until the icing is soft enough. Spread over the slice mixture. Refrigerate for a few hours. Cut into fingers.