Serves: 20 truffles1) Place the double cream in a heat-proof bowl and set the bowl over a pan of simmering water. Cook until heated through. Using a wire whisk, slowly stir the white chocolate into the warm cream until completely melted.
2) Whisk in the liqueur and vanilla. Cover and chill for 1 hour or until fairly firm but still pliable enough to scoop.
3) Preheat the oven to 180C/Gas mark 4. Place the chopped hazelnuts on a baking sheet and place them in the oven for 8 minutes. Cool to room temperature.
4) With 2 tsp or a 5cm ice cream scoop, make dollops of the chocolate mixture and place on a baking sheet lined with greaseproof paper. Refrigerate for about 15 minutes, until firm enough to roll into rough spheres.
5) Melt the dark chocolate in a heat-proof bowl set over a pan of simmering water. Drizzle the melted dark chocolate over 10 of the truffles. Roll the remaining truffles in the chopped nuts. Chill until ready to serve.