1 pound semisweet chocolate, cut into 1/4-inch chunks
3/4 cup, plus 2 tablespoons, heavy cream
5 tablespoons butter, softened and cut in chunks
1/2 cup unsweetened cocoa powder
Place the chocolate chunks into a large, heatproof bowl over a saucepan filled with hot (not boiling) water. Keep water hot by placing this arrangement of pot and bowl on a stovetop burner, set at about medium heat. Let chocolate mixture begin to slowly melt while you proceed with recipe.
In a small heavy saucepan, bring the cream just to a boil, stirring continuously. As soon as it begins to boil, remove from heat and pour it over chocolate chunks, stirring gently, but continuously, until chocolate has melted. Keep bowl positioned over hot water because this will help keep temperature at melting point. Once chocolate is smooth and creamy, stir in the butter, chunk by chunk, and continue stirring until mixture is well-blended and smooth. Chill mixture until it is very firm (for about 2 hours), but don't let it go overnight, or it will be too hard.
Working quickly so you don't melt chocolate, scoop firm chocolate with a teaspoon and shape into 1-inch balls (coat hands with cocoa and work quickly or chocolate will melt). Roll balls in the cocoa, chill, then store truffles in a sealed container. For an attractive presentation, place each truffle in a small paper or foil cup.
Makes about 24 truffles.