In a small heavy saucepan, combine 4 ounces semisweet chocolate, the dark chocolate, cream and cheese. Cook and stir over low heat until smooth.
Transfer to a small bowl; cover and refrigerate for 3 hours or until firm enough to shape.
Shape into 1-in. balls and place on waxed paper-lined baking sheets. Chill for 1-2 hours or until firm.
In a microwave, melt remaining semisweet chocolate; stir until smooth.
Dip balls in chocolate; allow excess to drip off.
Roll in pistachios. Place on waxed paper; let stand until set.
Store in the refrigerator.
