In large bowl, combine 8 oz chocolate pieces and butter.
In small saucepan, heat cream over low until simmering.
Remove cream from heat and spoon 1/2 cup into bowl with chocolate. Gently stir until chocolate begins to melt and mixture becomes smooth.
Slowly spoon remaining cream into mixture and stir until ganache is thick and shiny.
Spoon ganache into 2" deep baking dish and place in the freezer until it is the texture of fudge, about 30 minutes.
Cover a baking sheet with wax or parchment paper.
Remove ganache from freezer. To make truffles, form small balls using a melon baller or small spoon, and place each ball on prepared baking sheet. Balls do not need to be perfect.
When baking sheet is full, move truffles to freezer for 15 minutes.
Remove truffles from freezer and roll between hands to form even, circular balls. Return truffles to freezer.
In heat-safe bowl or top of double boiler, put remaining chocolate chips. Set the bowl or top of double boiler over simmering water. Heat, stirring constantly, until chocolate melted.
Remove chocolate from heat, stirring frequently until the chocolate begins to slightly set at the edges of the bowl.
Remove truffles from freezer. Carefully dip each truffle in melted chocolate, coating all sides. Remove with fork, letting extra chocolate drip off. Place finished truffles back on wax paper, cover with another sheet, and place in refrigerator for 5 minutes to set.