Line a baking tray with baking/parchment paper and set aside.
Place cookies into a food processor and process into very fine crumbs (reserve 1 - 2 teaspoons for sprinkling on top of the melted chocolate if you like).
250 g Lotus Biscoff cookies
Add sweetened condensed milk (not the whole tin) and mix well.
170 g sweetened condensed milk
Take approximately 1 tablespoon of the cookie mixture and form into a ball by rolling it between your palms, then place it on the prepared baking tray.
Repeat with the remaining mixture to create 16 balls.
Place the chocolate in a small glass bowl, and heat in the microwave on 50% power in 30-second bursts (mixing between each with a metal spoon) to melt.
200 g white chocolate melts
Working with 2 - 3 balls at a time, place the balls into the melted chocolate and use two forks to roll to coat.
Lift the balls out one at a time (using the forks), allowing excess chocolate to drip off (back into the bowl), then place them back onto the prepared tray.
Repeat for the remaining balls, drizzle with Biscoff spread (if using), sprinkle with reserved Biscoff cookie crumbs (if using), then place in the fridge to set.
Biscoff spread (slightly warmed) for drizzling
Take the truffles out of the fridge 5 to 10 minutes before serving.