Grease and line a 17 x 27cm slice tin with baking paper, leaving an overhang on all sides.
Place the biscuits in a food processor and process them to form fine crumbs.
Transfer the mixture to a bowl, then combine with coconut and finely grated zest of 1 lemon.
Place the butter in a small saucepan over medium heat to melt. Stir in the condensed milk.
Pour the melted mixture over the dry ingredients and stir to combine well.
Press the biscuit mixture into the prepared tin and refrigerate for one hour or until firm.
When set, ice with lemon icing.
To make lemon icing, sift the icing sugar in a bowl. Add melted butter and lemon juice and beat until smooth.
