Ganache isn’t strictly speaking temper-able, but the rate at which ganache cools and the types of crystals it forms are important. The more of the stable, “Form V”-type cocoa butter crystals you have in your ganache, the better its consistency will be. For that reason, a ganache should always be allowed to cool slowly at room temperature, and never cooled quickly in the refrigerator. Classic ganache, which is made of a 50-50 mixture of chocolate and heavy cream, is quite soupy when it’s made, then is traditionally left out on the counter overnight before it’s used. Several hours will suffice, though purists may howl. What does a long, slow cooling do for a ganache? It gives it a smoother, less grainy texture and prevents it from becoming greasy with separated cocoa butter.