My friend Laura used to make these for dessert after dinner parties. I lost her recipe so have taken what I remembered of it and added different ingredients to make these a bit more adult. You don't have to use the liqueur if you don't want to, if you do you can also use Kahlua or Tia Maria if you prefer. This bit has been added as a result of Andria's review - if you use any other biscuits apart from toffee pops (eg Twix) make sure that there is a lot more biscuit than toffee - otherwise the mixture may not harden. I have used Twix in the UK but put them in the freezer for a couple of hours before making. Also, these are not hard truffles anyway - they are quite soft but hold their shape well so long as they are refrigerated until just prior to serving.