This past weekend I set out to make some chocolate truffles for Valentine's Day. The dark chocolate and milk chocolate ganache both set up fine after I hit them with my immersion blender, but the white chocolate ganache stayed soupy and non-ganache-like. I'm guessing that it had something to do with the percentage of cacao in the chocolate, but I'm not sure. Has anyone else had similar problems? Is there a (home kitchen) way to get the white chocolate ganache to set up firm enough to roll into truffle form, or should I just stick with dark chocolate (and to a lesser extent, milk chocolate) from here on out for truffle making purposes?