Step 1

Grease a 3cm deep, 15.5cm x 25cm (base) slab pan. Line base and sides with baking paper, extending paper 2cm above edges of pan.

Step 2

Place condensed milk and butter in a small saucepan over medium heat. Cook, stirring, for 5 minutes or until smooth and combined. Remove from heat.

Step 3

Using a food processor, process biscuits until fine crumbs. Transfer to a bowl. Add coconut and lemon rind. Stir to combine. Add hot butter mixture. Mix well to combine. Press mixture over the base of prepared pan. Cover. Refrigerate for 1 1/2 hours or until firm.

Step 4

Make lemon icing: Sift icing sugar into a bowl. Add butter and lemon juice. Beat with a wooden spoon until smooth and combined. Spread icing over slice. Stand at room temperature for 30 minutes or until icing has set. Cut into pieces. Serve.