The FDA said to be called white chocolate, the candy must have at least 20% cocoa butter, 14% milk solids, and 3.5% milk fat — and no more than 55% sugar or other sweeteners. Vanilla is added for flavor, and a fatty substance called lecithin is in there as an emulsifier. The FDA's actions were partly in response to petitions from Hershey Foods and the Chocolate Manufacturers Association of America, who wanted to stop manufacturers from making imposter white chocolate using only vegetable oil or other cheaper fats instead of cocoa butter. Learn more about the FDA definition of white chocolate here.