Grease and line a 20cm (8") square baking pan/tin and set aside.
In a large bowl, place condensed milk, caramilk, butter, and vanilla.
375 g condensed milk, 100 g salted butter, 180 g caramilk chocolate, 1 teaspoon vanilla
Heat in the microwave in 30 second bursts (mixing between each burst) until melted.
Add in crushed biscuits and rice bubbles, mixing well to combine (it will be very sticky).
250 g Arnotts Marie biscuits, 80 g rice bubbles
Press base mixture into tin and smooth the top.