Place chocolate and cream in a microwave-safe bowl. Microwave on high for 1 minute. Stir until smooth.
Stir in liqueur. Refrigerate for 2 hours or until almost firm.
Roll 1 teaspoon of chocolate mixture into a ball. Place on a tray lined with baking paper. Repeat with remaining chocolate mixture. Roll half the balls in hazelnut and half in cocoa powder. Refrigerate until just before serving.