Preheat oven to 160 degrees celsius (fan-forced). Line a muffin tray with cupcake liners and set aside.
Crush the biscuits in a food processor (or with a rolling pin).
Place the butter into a microwave-safe bowl and melt on 50% power, in 30 second bursts.
Stir the butter through the biscuit crumbs until well combined.
Divide the mixture between the cupcake liners and press down. Bake for 5 minutes. Set aside.
Place the cream cheese into a large bowl. Beat with handheld beaters or a stand mixer until smooth.
Add the sour cream, caster sugar, vanilla extract, eggs and caramel sauce and beat until smooth and combined.
Chop the Twix bars into small chunks and stir through the cream cheese mixture.
Divide the mixture between the prepared muffin holes (filling almost to the top).
Bake for 20 minutes or until just cooked. Allow to cool completely.
Decorate with extra chopped Twix bars and drizzle with caramel sauce.
Store in an airtight container in the refrigerator for 3-4 days.