Put the whipping cream, salt and your herb of choice in a saucepan over a low heat and bring to scalding point, then reduce the heat to its lowest setting and gently simmer for about 20 minutes to allow the cream to absorb the flavour. Do not boil.
Remove from the heat, stir in the sugar and allow to cool until it reaches a temperature of 20°C (room temperature).
Whisk the butter in a bowl using an electric stand or hand-held mixer until it forms a soft smooth mass. Gradually add the cream mixture, beating continuously. Add some liqueur, if using, at this stage.
If the mixture curdles (a sign that it is too cold), reheat over a pan of barely simmering water until it re-emulsifies. If it is too soft, set the bowl over iced water and heat.
Line one or two baking trays with baking parchment. Fill an icing bag fitted with a size 2 piping bag nozzle (approx. 3cm long and 1.8cm wide) with the truffle mixture and pipe little rounds about the size of a nutmeg onto the parchment; this amount will make around 50 truffles. Transfer the tray(s) to the freezer. After about 45 minutes, remove.
Meanwhile melt the chocolate over a pan of barely simmering water, making sure the bowl doesn’t touch the water, then set aside to cool until it reaches 40°C. Put the Green & Black’s Cocoa Powder in a shallow bowl or on a plate and have a sieve to hand.
Dip the truffle fillings into the melted chocolate then lay them in the cocoa powder. When they have set, transfer a few at a time, to the sieve and shake off excess cocoa powder. Store the truffles in a sealed box in the fridge or, to keep them fresh for longer, in the freezer.
The time quoted above is an estimate of the time needed until the recipe is ready to eat, allowing for preparation, baking and resting.
As you might expect from Green & Black's, this recipe is indulgent and should be enjoyed as a treat..