Finely chop the dark chocolate and place it in a heatproof bowl. In a saucepan, heat the heavy cream until it simmers. Pour over chocolate, add coffee, and stir until smooth.

Cover the bowl with plastic wrap and refrigerate for 1-2 hours until firm.

Use a melon baller or cookie scoop to portion and roll the ganache into balls about 1 inch in diameter. Place on a parchment-lined sheet.

Melt the milk chocolate in a microwave-safe bowl. Dip each truffle in the melted chocolate, then place on parchment paper to set.

Let truffles sit at room temperature for 30 minutes or refrigerate for 15 minutes until chocolate hardens.