METHOD

1. Line a 20cm x 30cm slice tin with non-stick baking paper. Place the biscuits in a food processor and process into fine crumbs. Add the butter and process until combined. Using the back of a spoon, press the mixture into the base of the tin. Set aside in the refrigerator. 
   
2. Place the warm water in the bowl of an electric mixer, sprinkle with the gelatine and stir to combine. Set aside for 5 minutes or until the gelatine is absorbed. Place the sugar, glucose and extra water in a small saucepan over medium heat and cook, stirring, until the sugar has dissolved. Increase the heat to high and bring to the boil. Cook, without stirring, for 5–7 minutes or until the temperature reaches 115°C (240°F) on a sugar (candy) thermometer. In a thin, steady stream, gradually pour the hot sugar syrup into the gelatine mixture, beating on high speed. Add the vanilla and beat for 3–4 minutes or until the mixture is thick and fluffy. Working quickly, spoon the mixture into the tin, smoothing it over the biscuit base with a greased spatula. Refrigerate for 10 minutes or until just firm. 
   
3. Place the chocolate and oil in a heatproof bowl over a saucepan of simmering water (the bowl shouldn’t touch the water) and stir until melted and smooth. Allow to cool for 10 minutes. 
   
4. Spread the caramel evenly over the marshmallow layer. Refrigerate for 10 minutes. Top the slice with the chocolate, spread evenly and refrigerate for a further 20 minutes or until firm. Use a hot sharp knife to cut the slice into bars to serve. Makes 8
   

Tip: You can keep this slice refrigerated, in an airtight container, for up to 1 week.