Quickly rinse a pan with cold water and then pour in the double cream. Bring to boiling point but do not allow to boil for more than a second. Add the plain chocolate and stir until dissolved. Return to the heat if necessary but do not allow to boil. Pour into a bowl ready for mixing.
When the mixture has reduced to room temperature beat in the Grand Marnier, orange rind and the chopped almonds. Mix well
Refrigerate until the paste is cold enough to roll into balls.
Take a spoonful of mixture and roll into a ball. Keep your hands as cold as possible. Then lightly roll the ball into powdered cocoa. Alternatively use Icing Sugar or Chocolate Vermicelli.
As an alternative to using cocoa (which seems to give a very bitter and powdery taste) or white icing sugar (which soaks into the mixture) I like coating the truffles with chocolate. Melt the chocolate in a basin over hot water and dip each truffle into the hot chocolate. Allow to drip and then place on greased proof paper to dry. White chocolate takes longer to dry. Then drizzle black or white chocolate over the truffles.
Place in paper cases and arrange on a serving dish. Keep refrigerated until served.
I have tried this with white chocolate and it works quite well except that the mixture needs more almonds otherwise it does not seem to set.