Buttercream

I've had a request for buttercream truffles, but I'm not sure exactly what that is. A lot of recipes online are just leftover buttercream frosting. I found one with cream cheese which sounds wrong. My chocolate textbook 'Chocolates & Confections' doesn't say anything about buttercreams in the index. Is a buttercream a butter ganache?

Please help me clarify what kind of recipe I should be looking for. Thanks!