Place white chocolate Tim Tams and Peppermint Crisp bars into the Thermomix bowl and crush on Turbo until they resemble fine crumbs.
Add the cream cheese and mix on Reverse, Speed 2 until well combined (scraping down the sides of the bowl occasionally).
Roll into 1 inch sized balls and place on a tray lined with baking paper into the freezer for 30 minutes.
Place chocolate into a clean Thermomix bowl and melt for 3 minutes, 50 degrees, Speed 3, scraping the sides occasionally. Pour the melted chocolate into a bowl.
Place the balls into the bowl of melted chocolate (in batches) and use two forks to roll the truffles around until they are completely coated.
Remove balls with the forks and allow any excess chocolate to drip off.
Place back onto the baking paper lined tray. Decorate with sprinkles if desired.
Place into the fridge to set for 1 hour.