Line a baking tray with greaseproof paper.
In a medium saucepan over medium high heat, combine the butter and cream.
Bring to the boil then remove from heat.
Stir in 100g chopped chocolate, orange liquor (if using) and orange zest.
Stir until smooth.
Pour truffle mixture into a shallow baking dish.
Chill for 2 hours or until firm.
Shape the truffle mixture using a teaspoon.
Arrange them as you go on the prepared baking tray.
Chill for 30 minutes or until firm.
Melt remaining 100g chocolate with the oil, stirring until smooth then cool.
Lower the truffles, one at a time, into the melted chocolate mixture.
Use a slotted spoon to lift truffles out of the chocolate, allowing any excess chocolate to drip back into the pan before transferring back onto baking tray.
Chill until set then serve or wrap up for another date.