Chop dark chocolate and place it in a heatproof bowl. Heat heavy cream in a saucepan until just boiling. Pour cream over chocolate and let sit for 3-5 minutes before stirring until smooth.

Mix in strong brewed coffee or espresso into the ganache until fully incorporated.

Cover the bowl with plastic wrap and refrigerate the ganache for at least 2 hours.

Remove the ganache and roll it into small balls, about 1 inch in diameter, then place on a parchment-lined baking sheet.

Melt milk chocolate in a microwave-safe bowl, stirring every 30 seconds. Dip each ganache ball into the melted chocolate and place back on parchment.

Let the coated truffles sit at room temperature for about 30 minutes to set.