Grease and line a 20cm x 30cm (8" x 12") baking tin/pan and set aside.
Place Scotch Finger biscuits (375g) in a food processor and process into fine crumbs.
Then add Clinkers (300g) to crumbs in processor, and process again to chop Clinkers.
Meanwhile, in a large bowl combine the condensed milk (395g), salted butter (100g), and 110g of the Caramilk chocolate (approx one full family-sized block MINUS 3 rows) and microwave on half power in 1-minute bursts until melted and mix to combine.
Add the biscuit crumb mixture to the condensed milk mixture and mix to combine. Press mixture firmly into the greased and lined tin.
In a small bowl place the remaining Caramilk chocolate (250g - approx one family-sized block PLUS 3 rows) and vegetable oil (1½ tbsp) and microwave in 30-second bursts until melted then mix to combine.
Pour melted chocolate evenly over the base and refrigerate until set.