Line and grease a 18 x 32cm slice tray with baking paper and set aside.
Combine the butter, sweetened condensed milk and golden syrup in a microwave-safe bowl and melt on 50% power, 3-4 minutes, or until melted.
Add the crushed biscuits, coconut and licorice allsorts and stir until just combined.
Press the mixture into the base of the prepared pan and set aside for 30 minutes to set.
Place the milk chocolate and vegetable oil in a microwave-safe and melt on 50% power, 3-4 minutes, stirring every 30 seconds until just melted.
Pour the melted chocolate over the slice and place into the fridge to set.