In a medium saucepan heat whipping cream and butter over medium heat just to boiling. Remove saucepan from heat. Add dark chocolate, but do not stir. Cover and let stand at room temperature for 5 minutes. Stir until smooth. Stir in coffee liqueur. Cover and chill for 1-1/2 to 2 hours or until almost firm, stirring once or twice.
Line a baking sheet with parchment or waxed paper. Drop chocolate mixture in 1-inch mounds onto prepared baking sheet. Chill about 1 hour or until firm. Shape chilled mounds into 1-inch balls. If desired, insert a wooden crafts stick into each ball; return to baking sheet. Cover and freeze for 30 minutes.
Place white chocolate and shortening in a large microwave-safe bowl. Microwave, uncovered, on 50 percent power (medium) for 2 to 2-1/2 minutes or until melted, stirring twice. Cool slightly. Dip balls, one at a time, into melted chocolate. Let excess chocolate drip off balls. Place truffles on a baking sheet lined with parchment or waxed paper. Immediately sprinkle each truffle with some of the coffee crystals if desired. Chill about 30 minutes or until set.
Cover tightly and chill for up to 2 weeks or freeze for up to 1 month. Let truffles stand at room temperature about 30 minutes before serving. Makes about 48.