Shave chocolate into tiny pieces; set aside. In a large saucepan, blend together cream, liqueurs and vanilla and heat until the cream begins to scald; remove from heat. Add the chocolate pieces and whisk for 2 to 3 minutes or until the ganache is satiny and smooth, with no lumps of cream or chocolate. Transfer ganache to a bowl and allow to cool (at room temperature) below 90 degrees. Cut butter into small pieces and add, piece by piece, to the ganache, stirring well. Allow ganache to cool and become somewhat firm. Line a baking pan with parchment paper. Using a Small ice cream scoop, shape ganache into mounds and place them on the parchment. Refrigerate until set. Dust hands with cocoa powder; shape each mound into uniformly-shaped balls and refrigerate.

Melt chocolate in a double boiler. Arrange two sheets of parchment paper on work surface. Drop a truffle into melted chocolate, retrieve with fork and tap the truffle 4 or 5 times against the surface of the chocolate to get rid of the excess. Then scrape the sides of the pan with the fork and drag the fork (with the truffle on it) across one sheet of parchment paper to remove more chocolate. Place the finished truffle on the clean parchment; repeat with remaining truffles. If desired, use melted white chocolate to pipe designs onto tops of truffles.