How can I make a vanilla ganache which does not taste of white chocolate?
Use a soy and vegetable-fat based white chocolate like Oppenheimer Kosher white chocolate chips. They are quite sweet, but lag behind on the chocolate-y taste. They temper well and behave in most ways I've used them like regular chocolate chips, except that for white chocolate taste they are a bit bland. These would make a good vehicle for a lighter but still sugary vehicle for vanilla.