Directions

1. Put the cream and butter in a saucepan. Heat gently until the butter has melted and the mixture starts to simmer. Put both types of chocolate into a large heatproof bowl then pour the hot cream mixture on top of the chocolate. Leave to sit for a minute or two then stir until all the chocolate has melted, finally stir in the prosecco. Chill the mixture for 4 hours or overnight if you can.
2. Line baking trays with foil. Pipe the mixture, shaping into 25 small balls on the trays. Now put the trays in the freezer for 1 hr or until you're ready to serve them. Put the milk chocolate for coating into a heatproof bowl and heat in the microwave until melted, stirring after every 30-second blast. Alternatively set the bowl over a pan of simmering water to gently melt the chocolate. Drop a frozen truffle into the melted chocolate and turn it over with a spoon to coat it, then place back onto the foil-lined tray. Repeat with the rest of the truffles. The coating should set in about 5-10 mins.
3. Once set, dust a plate or bowl with icing sugar then roll a truffle around on it to coat. Repeat with the rest of the truffles, re-dusting the plate when necessary, then place into boxes or on a plate to serve.