Line a small dish with non-stick baking paper.
Heat cream in a saucepan until just below boiling.
Remove from heat, add chopped dark chocolate and coffee, stir until smooth.
Pour mixture into prepared dish, chill for 2 hours until firm.
Scoop small portions, roll into balls, refrigerate for 30 minutes.
Melt milk chocolate over simmering water, cool slightly.
Dip each truffle into melted chocolate, remove with forks, and set on lined tray.
Chill for 30 minutes until coating is crisp.
Optional: drizzle with remaining chocolate.