Want to make champagne buttercream frosting? If you want to tweak the vanilla buttercream recipe I linked to in order to make a champagne buttercream frosting, you could try substituting the milk (or most of the milk) in the light and airy vanilla buttercream frosting recipe for champagne (or pink champagne). While I haven't tried it, that seems pretty in line with what I have seen from champagne buttercream frosting recipes online.