Step 1

Grease a 20cm square cake tin and line it with two sheets of baking paper cut to the width of the tin, crossed over so there is a double layer in the base, and all four sides are covered, leaving plenty of overhanging paper to make it easy to lift out the finished slice.

Step 2

In a food processor, blitz biscuits into a fine crumb. Add melted butter and 1/3 cup condensed milk and blitz to combine. Tip into prepared tin and press down with the back of a large spoon to form a smooth even layer.

Step 3

Place remaining condensed milk with the Caramilk in a metal or glass bowl set over a saucepan of simmering water. Stir occasionally until melted and smooth. You can also do this step in the microwave - work in short bursts, stirring in between, until melted.

Step 4

Pour over biscuit base and smooth the top. Refrigerate for at least 1 hour to set.

Step 5

Use overhanging paper to gently ease the slice away from the edges and lift out of the tin. Cut into 16 equal squares.