- In a double boiler or in a microwave, melt the dark chocolate chips and butter together.
- Using an electric hand mixer or standing mixer, beat heavy cream until there are soft peaks.
- Let chocolate cool for a minute and then add the whipped cream; gently mix.
- Chill the chocolate mixture until it is hard enough to be rolled into balls.
- Measuring out a heaping teaspoon, quickly roll the chocolate mixture into a ball.
- Roll the ball in cocoa powder and chill.
Truffles can be kept in the refrigerator for 1-2 weeks, but they are best served at room temperature.