That was fast. Reader Linda writes in to ask whether chocolate buttercreams are the same thing as chocolate frostings. The answer is no. Chocolate frostings — milk, dark, and white — are more like ganaches than they are like buttercreams, which is to say they are chocolates made spreadable by the addition of fat or oil. A standard chocolate frosting is simply a whipped combination of melted chocolate and soft butter. White chocolate frosting is usually a combo of white chocolate and butter, though it can also be made with a neutral-tasting oil. Myself, I tend not to like frostings so much on the outside of cakes, but enjoy them on the inside, as a filling, where their density is more of a virtue than a drawback.