I use heavy cream and make it in the food processor. Break chocolate into pieces and process in food processor until very fine. Heat cream to the boiling point and, with the motor running, pour through the feed tube in a steady stream. Process a few seconds until smooth. Transfer to a bowl and cool completely. Allow to cool for several hours or until frosting consistency. Have never had an issue. Jo from Ciccio Cakes uses a stick blender. https://www.facebook.com/notes/ciccio-cakes/pastry-chef-secrets-chocolate-ganache/581157415240484 Since I gave my stick blender to my daughter, I use the food processor.
