Form truffle centers by filling a pastry bag with the ganache. With a half inch tube, pipe 3/4 inch balls onto a parchment-lined cookie sheet. Start by holding the tip just above the sheet, squeezing until the ball forms. Finish by moving the tip sideways to avoid a pointy ganache peak.
Refrigerate one hour before coating.
Coat the centers by dipping in chocolate. If you will roll the truffles in nuts, cocoa, or something else that hides the cloture, do a quick temper and arrange your workspace from one side to another like this, from right to left if right handed: