Step 1

Preheat oven to 180C/160C fan-forced. Grease a 20cm x 30cm lamington pan. Line base and sides with baking paper, extending paper 2cm above edges on all sides.

Step 2

Using a food processor, process the biscuits until finely chopped and mixture almost forms a paste. Press mixture over base of prepared pan. Refrigerate for 10 minutes. Bake for 10 minutes or until just firm to touch.

Step 3

Meanwhile, using an electric mixer, beat cake mix, condensed milk, egg and 1/2 cup of the shredded coconut until well combined. Spread evenly over prepared base. Bake for 25 to 30 minutes or until a skewer inserted into centre of slice comes out with moist crumbs clinging and top is just firm to touch.

Step 4

While slice is still hot, combine icing sachet with 2 tablespoons hot water until smooth. Pour over top of slice, spreading evenly with a spatula. Sprinkle with remaining shredded coconut. Set aside to cool completely. Cut into 18 pieces. Serve.